Locations of all Vivillon patterns in New Pokémon Snap
In New Pokémon Snap, you will venture out into the Lental region, a group of islands possessing a wide range of biomes housing many types of Pokémon. Among them is Vivillon, a Pokémon you can almost certainly encounter in virtually every biome imaginable, as it can perfectly adapt to any environment by sporting different patterns. These patterns act as a collectible for upcoming photographers and are sometimes hard to spot in the wild. Therefore, I have compiled a complete list of all 20 Vivillon patterns you can come across on the different islands of Lental. Hopefully, this will help you to fill out your Photodex.
Vivillon (Meadow Pattern)

Florio Nature Park: Park (Day)
Encountering a Vivillon with a Meadow Pattern is straightforward: it is the first Vivillon you will face in this game, likely, the very first Pokémon overall. It flutters around the beginning of the Florio Nature Park during the daytime. Snap a picture to get its entry. Alternatively, you will get quite a few opportunities at the end of the level as many Meadow Pattern Vivillons will be gathering in the flower meadow.
Secret Side Path: Side Path (Day)
If for whatever reason, you haven't snapped a picture of Vivillon's Meadow Pattern in the Florio Nature Park, you can make up for it in the Secret Side Path during a daytime exploration. Just snap an image of it near Torterra to get its entry.
Vivillon (Garden Pattern)

Florio Nature Park: Park (Day)
Next up: the Garden Pattern. During the daytime, head over to the end of the Florio Nature Park. When you come across the shield at the beginning of the flower meadow, turn around. There, you will see a greenish Vivillon performing some loop-the-loops. Wait for a bit, and it will start to follow you into the flower meadow. Snap a close-up picture to guarantee a 2-star diamond-rated image.
Secret Side Path: Side Path (Day)
During the day, you can encounter another Garden Pattern Vivillon on the Secret Side Path. To make it appear, you must throw an Illumina Orb at the Vivillon resting on Torterra's back and play the melody right after. Shortly after, the Vivillon will begin to flutter around, and the Garden Pattern Vivillon will join in. Both will play for a while but soon move out of your field of view. So, be quick and snap a photo!
Secret Side Path: Side Path (Night)
The last Garden Pattern Vivillon will be encounterable on the Secret Side Path during nighttime. Follow whatever path you fancy, and after the second tree stump, close to the end of your route, you will see your desired Vivillon flapping around. Get a close-up, and be done with this pattern!
Vivillon (Marine Pattern)

Blushing Beach: Beach (Day)
You will find the first Marine Pattern Vivillon on the Blushing Beach during the daytime. Just follow the regular route, and once you come close to the rocky arch, watch out for a blue Vivillon crossing your path. Capture it on the photo, and you will get its Photodex entry.
Blushing Beach: Beach (Night)
If you fancy a different time of day, visit the Blushing Beach during the nighttime. Right at the beginning of the course, a swarm of Vivillon will fly near the shoreline. You are just a click away from adding this pattern to your Photodex.
Barren Badlands: Badlands (Night)
If you want to find the Marine Pattern Vivillon in an entirely different biome, head to the Barren Badlands during nighttime. At the start of the level, three Vivillon are fluttering in the same general direction as you. Toss an Illumina Orb towards each of them and then take the alternative route. To unlock it, toss an Illumina Orb at a dust cloud to make a Diglett appear, and then hit it with a Fluffruit. Do this thrice, and throw an Illumina Orb at the Crystabloom nearby. Now follow the route as usual until you reach a large open ravine. There, on the right side, should be another Crystabloom. Toss an Illumina Orb at it once the Vivillons are close to it. Watch how several different Vivillons from all over Lental appear and gather in the ravine. Among them is your desired Vivillon.
Vivillon (Ocean Pattern)

Maricopia Reef: Reef (Evening)
If you are looking for a Vivillon sporting the Ocean Pattern, you should visit the Maricopia Reef during the evening and follow the route until you reach the giant whirlpool. Then, look into the distance, and you should be able to spot two colorful Vivillons. Take a picture, and you can add this type of Vivillon to your Photodex.
Barren Badlands: Badlands (Night)
The Ocean Pattern of Vivillon is also encounterable in the Barren Badlands. Right at the start of the course, three Vivillon are flying in the same general direction as you. Toss an Illumina Orb towards each of them and then take the alternative route. To unlock it, toss an Illumina Orb at a dust cloud to make a Diglett appear, and then hit it with a Fluffruit. Do this thrice, and throw an Illumina Orb at the Crystabloom nearby. Now follow the route as usual until you reach a large open ravine. There, on the right side, should be a Crystabloom. Toss an Illumina Orb at it once the Vivillons are close to it. Illuminating the Crystabloom will draw in many different Vivillons from all over the Lental region. Among them is an Ocean Pattern Vivillon. Make sure to take pictures of all of them!
Vivillon (Jungle Pattern)

Founja Jungle: Jungle (Day)
You will come across a Vivillon with a Jungle Pattern during a daytime trip through the Founja Jungle. Follow the path until you reach the cliff, where you step onto a cliffside hanging tree trunk. Next, pan your camera towards the general direction of the upcoming waterfalls and be ready to start throwing Illumina Orbs at the Liepard, which will jump onto the big stone pillar further ahead. Upon hitting it before it lays down, it will jump off it and continue to sprint into the undergrowth. Now, take the alternative path leading behind the waterfalls. Here, you can take a picture of a Jungle Pattern Vivillon sticking to a wall to your right. Task accomplished.
Founja Jungle: Jungle (Night)
Staying inside the Founja Jungle, this Vivillon is also active at night. Follow the path until you reach the lake by the waterfalls. Wait until you're close to the Morelulls that reside on a hill to your right. Use the scan, and you should see three ??? behind the Morelull appear. Immediately after you scan, use the melody function of your NEO-ONE and use the scan feature one more time. You should be able to observe that the three ??? start moving. Shortly after, three Vivillon should appear from the undergrowth, among them two Jungle Pattern Vivillons. Take a photo to add this pattern to your Photodex.
Mightywide River: River (Day)
If you unlocked the Migthywide River daytime course already, you should be able to take a picture of Vivillon here, too. To make it appear, you must illuminate the first Crystabloom to the left once you reach the waterfall you raft down on. This undertaking can be tricky, but if you cannot hit it immediately, turn around upon arriving at the end, and you should still be able to hit it regardless. Once accomplished, pan your camera slightly to the right and upward to spot two Vivillon with the desired pattern fluttering above the hillside.
Mightywide River: River (Night)
If you are more interested in nighttime shots for your Photodex, you can also spot a Vivillon rocking a Jungle Pattern on the Migthywide River during nighttime. There are two occasions where you can take a decent photo. The first one is right at the start of the course. Pan your camera upward, and you should be able to spot two Vivillon soon after. For an excellent loop-the-loop close-up shot, throw an Illumina Orb at one of them. Additionally, at the end of the course, right beside the marker that identifies the course's end, there will be a Vivillon with a Jungle Pattern beside one with a River Pattern. Here, you can quickly get a picture of both, crossing two patterns of your list simultaneously.
Outaway Cave: Cave
If unsatisfied with the locations listed above, you can always venture into the Outaway Cave to get a proper shot of a Jungle Pattern Vivillon. Take the alternative route to the giant crystal formations and follow the path until the end of the course, where you come across a lush undergrowth inside a cavern. Here, two Vivillon will tend to their business–happily fluttering around the cave.
Barren Badlands: Badlands (Night)
Lastly, there's one more opportunity to get a photo of a Jungle Pattern Vivillon in the Lental region. To get it, head over to the Barren Badlands during nighttime. Right at the start of the course, three Vivillon are flying in the same general direction as you. Toss an Illumina Orb towards each of them and then take the alternative route. To unlock it, toss an Illumina Orb at a dust cloud to make a Diglett appear, and then hit it with a Fluffruit. Do this thrice, and throw an Illumina Orb at the Crystabloom nearby. Now follow the route as usual until you reach a large open ravine. There, on the right side, should be a Crystabloom. Toss an Illumina Orb at it once the Vivillons are close to it. Witness how a large swarm of Vivillons from all over Lental appear and gather in the ravine. Among them is a Jungle Pattern Vivillon.
Vivillon (Monsoon Pattern)

Founja Jungle: Jungle (Day)
To capture a photo of a Vivillon with a Monsoon Pattern, you have to head over to the Founja Jungle during the daytime. Take the first alternative route you encounter that leads into the swamp. Here, you have to throw an Illumina Orb at Aipom, which shortly stops on its way and waves at you. If done correctly, it will cut the tall grass revealing a path in which several Vivillons with the Monsoon Pattern have gathered. Upon disturbance, they will head out of the cave. It would be best to take a picture to get its Photodex entry.
Vivillon (River Pattern)

Founja Jungle: Jungle (Night)
Like many types of Vivillon, this one is also encounterable in the Founja Jungle during nighttime. Follow the path until you reach the lake by the waterfalls. Wait until you're close to the Morelulls that reside on a hill to your right. Use the scan, and you should see three ??? behind the Morelull appear. Immediately after you scan, use the melody function of your NEO-ONE and utilize your scan one more time. You should be able to observe that the three ??? start moving. Shortly after, three Vivillon should appear from the undergrowth, among them a River Pattern Vivillon. Take a photo to add this pattern to your Photodex.
Mightywide River: River (Night)
Additionally, you can also encounter a River Pattern Vivillon during nighttime while exploring the Mightywide River. To find it, you must take the alternative route leading behind the vines covering up an entrance into a short cave system. There, you'll find several Vivillon enjoying the chillness of the stones. Again, as always, you should take a photo. Moreover, at the end of the course, right beside the marker that identifies the course's end, there will be a Vivillon with a River Pattern beside one with a Jungle Pattern. Here, you can quickly get a picture of both, crossing two patterns of your list simultaneously.
Vivillon (Sandstorm Pattern)

Sweltering Sands: Sands (Day)
You can find the Sandstorm Pattern Vivillon during a daytime trip through the Sweltering Sands. Just follow the regular route, and after passing the oasis, you will come to an area in the dunes with three giant pits harboring several Trapinch and a Pinsir. Here, two Vivillons will be happily fluttering around. Snap a picture, and you can cross the Sandstorm Pattern off your list.
Vivillon (Savanna Pattern)

Sweltering Sands: Sands (Night)
You will come across this Vivillon in the Sweltering Sands during a nighttime trip. For it to appear, you must throw two Fluffruit each at the Lycanrocs nearby. Then, turn around and throw an Illumina Orb at the Crystabloom in the oasis. Now, wait a short while, and three Vivillon should appear, among them, two Savanna Pattern Vivillons. Snap a photo and be done with it. You can also snap a picture of a Sun Pattern while at it, crossing two patterns off your list while out on your trip.
Barren Badlands: Badlands (Night)
However, if you want a photo of a Savanna Pattern Vivillon in another biome, head to the Barren Badlands during the nighttime. Right at the beginning, you will have multiple opportunities to get a good close-up shot of this type of Vivillon. But, more importantly, several different Vivillon types will be scattered around the general area, resting on trees or stones. So, get a photo of each variant to ease the workload!
Vivillon (Sun Pattern)

Sweltering Sands: Sands (Night)
Vivillon's Sun Pattern can first be encountered in the Sweltering Sands during a nighttime trip. For it to appear, you must throw two Fluffruit each at the Lycanrocs nearby. Then, turn around and throw an Illumina Orb at the Crystabloom in the oasis. Now, wait a short while, and three Vivillon should appear, among them, a single Sun Pattern Vivillon. You will add this variant to your Photodex if you take a picture. Also, you can snap a photo of a Savanna Pattern while at it, crossing two patterns off your list while out on your trip.
Barren Badlands: Badlands (Night)
However, if you want a photograph of a Sun Pattern Vivillon in the Barren Badlands, head there during nighttime. At the beginning of the course, you will have multiple opportunities to get a good close-up shot of this type of Vivillon. But, more importantly, several different Vivillon types will be scattered around the general area, resting on trees or stones. So, use this opportunity to cross as many Vivillon types off your list as possible!
Vivillon (High Plains Pattern)

Fireflow Volcano: Volcano
A Vivillon with the High Plains Pattern can be found in the Fireflow Volcano. To get a glimpse, you have to venture into the volcano and take the alternative route leading into the cavern with the blue magma falls. Continue to the end of the course until you reach the last cavern that opens up to the sky. There, high above is a Luxray sitting on a ledge. Throw an Illumina Orb at it to stir it. If done correctly, it will run away, and shortly after that, two Vivillons sporting the High Plains Pattern will appear in the sky above you. If you take a picture, you will add it to your Photodex.
Barren Badlands: Badlands (Night)
However, you can also get a photo of a High Plains Pattern Vivillon in the Barren Badlands, so head over there during nighttime. At the start of the course, you will have multiple opportunities to get a good close-up shot of a High Plains Pattern Vivillon. But, more importantly, there will also be several different Vivillons scattered around the general area, resting on trees and stone pillars. So, if you take a picture of each type, you will cross off multiple Vivillon types on your list!
Vivillon (Elegant Pattern)

Elsewhere Forest: Forest
To get a picture of Vivillon's Elegant Pattern, head over to the Elsewhere Forest and progress through it until you reach the second foggy portion. Here, you have to play through Deerling's event to make the Vivillon appear in the end. Therefore, activate the first two Crystablooms you come across, and then, once you get to the Crystablooms situated right behind each other, only illuminate the latter. Then, progress further until you come across another Crystabloom. Activate this one too, and watch an Espeon, Deerling, and Sawsbuck gather around it. Now, take the alternative route. Arriving at the next section of the map, use your NEO-ONE's scan function once you see an Espeon on a hill to the left. It will jump off it, and then you have to feed it a Fluffruit. While Espeon is eating, throw an Illumina Orb at it to make it jump onto the closeby rock. Now, throw yet another Illumina Orb at it to make it run away. Continue down the path until you reach a sunlit opening with a Crystabloom in the middle. Light it up and witness a gathering of all four types of Sawsbuck and their Deerling. If all of them have gathered, play the melody, and three Vivillons sporting the Elegant Pattern will appear from one of the paths the Sawsbucks came from and will continue to cross your path. Take a photo to add this beautiful type of Vivillon to your Photodex.
Vivillon (Tundra Pattern)

Shiver Snowfields: Snowfields (Day)
The Tundra Pattern Vivillon can be spotted on a trip through the Shiver Snowfields during the day. After climbing the snowy hill at the beginning, you will come to a narrow crack in the ground in which a Vivillon will be resting at a wall. Take a close-up shot to get an easy 1-star diamond-rated image for your Photodex and the Tundra Pattern entry on top of it!
Vivillon (Polar Pattern)

Shiver Snowfields: Snowfields (Day)
To find a Vivillon with a Polar Pattern, you have to head over to the Shiver Snowfields during the day and take both alternative routes to reach an icy cavern in which a Polar Pattern Vivillon resides. Then, try to align your camera to get a good shot at it.
Barren Badlands: Badlands (Night)
However, there's another opportunity to capture this type of Vivillon in a photo! Head over to the Barren Badlands during nighttime. Right at the start of the course, three Vivillon are flying in the same general direction as you. Toss an Illumina Orb towards each of them and then take the alternative route. To unlock it, toss an Illumina Orb at a dust cloud to make a Diglett appear, and then hit it with a Fluffruit. Do this thrice, and throw an Illumina Orb at the Crystabloom nearby. Now follow the route as usual until you reach a large open ravine. There, on the right side, should be a Crystabloom. Toss an Illumina Orb at it once the Vivillons are close. Watch how numerous Vivillons from all over Lental appear and gather in the ravine. Among them is a Polar Pattern Vivillon. Make sure to take pictures of all of them!
Vivillon (Icy Snow Pattern)

Shiver Snowfields: Snowfields (Night)
To capture a Vivillon with an Icy Snow Pattern on a photo, you have to head over to the Shiver Snowfields during the night and take both alternative routes to reach the icy cavern in which two Vivillon roam around. Then, snap a picture of it to add it to your Photodex.
Vivillon (Archipelago Pattern)

Outaway Cave: Cave
For this Vivillon to appear, you have to complete the game first. Then, head to the Outaway Cave and choose the alternative route leading to the giant crystals. Once you enter the enormous open cavern, throw Illumina Orbs at Mawile and the two Carbink to make a Diancie appear. Now throw an Illumina Orb at her, too, to soothe another Mawile down the path. This endeavor allows you to traverse another alternative route, leading to another small chamber full of lush foliage. Finally, throw an Illumina Orb at the Crystabloom to make an Archipelago Pattern Vivillon appear. You're now one photo away from adding this pattern to your Photodex!
Vivillon (Continental Pattern)

Ruins of Remembrance: Ruins
To get a shot at Vivillon's Continental Pattern, you must hit each Crystabloom inside the Ruins of Remembrance with an Illumina Orb; the two Crystablooms outside the ruins are not relevant for this. After hitting all five Crystablooms, turn around and wait a little bit. Soon after, three Vivillons adorned with the Continental Pattern will appear above the large root you crossed just moments ago. As always, take a photo to get its Photodex entry!
Vivillon (Modern Pattern)

Elsewhere Forest: Forest
While in the autumn part of the Elsewhere Forest, play the melody to make Serperior go over to Deerling. A Sawsbuck will also join in. Then you have to throw an Illumina Orb at Serperior to make it teach Deerling an attack move; you should take a photo of that. Afterward, look to the right in the sky to see a Vivillon rocking a Modern Pattern. Again, take a picture and be done with this pattern.
Vivillon (Fancy Pattern)

Research Camp
This Vivillon is only encounterable at the Research Camp. To find it, you have to start beside the NEO-ONE research vessels. If you did, follow the path and throw a Fluffruit into the tree on the right side by the Research Camp's entrance; if you struggle to determine which one, watch out for the tree full of Starly. Upon hitting the tree, the Starly will take off. Wherever they land again, a Vivillon with a Fancy Pattern will pass through the foliage. Snap a pic, and you got another pattern for the Photodex!
Vivillon (Poké Ball Pattern)

Research Camp
For Vivillon's Poké Ball Pattern, you must start at the Research Camp's entrance. If you did, follow the path until you reach Dedenne. Then, throw it off the NEO-ONE by hitting it with a Fluffruit. After falling, it will run over to a spot in the grass and clean itself. From there, you can lure it towards the bushes with two to three Fluffruit in a row. If done right, it will run into the foliage behind the bushes and cause a Vivillon with the Poké Ball Pattern to appear.