What are all the Pokemon you can find?

I can't tell u all the pokemon, but have you found the 3 dancing jiggypuff's...

Beach Level:
Pidgey, Doduo, Butterfree, Pikachu, Lapras, Snorlax, Meowth, Scyther, Eevee, Chansey, Kangaskhan, Magikarp
Scyther: Throw a Pester Ball at either of the tall grass masses when the rustling comes close.
Lapras: Look to the sea periodically. Snap Lapras at the primary beach, and then by the first grassy field (just past Meowth). When you come near Kangaskhan, you'll see him again, but ready to give you a great picture there!
Snorlax: Throw a Pester Ball at it (just past the primary beach) and it will scratch itself. Play a song to see him dance (it's a bit funny!).
Chansey. Throw an apple at the rolling mass in which Eevee is in pursuit of.
Sign: Kingler: Look to the rocks at the primary beach.

Tunnel Level:
Pikachu, Electrode, Electabuzz, Kakuna, Zubat, Zapdos, Magikarp, Diglett, Dugtrio, Magnemite, Magneton
Kakuna: They drop down low when an Electrode explodes in the first chamber.
Zapdos: Coax Pikachu near the egg and play your flute.
Dugtrio: Photograph Diglett each time it comes up. After four snaps Dugtrio will meet with Pikachu. Two or three will arrive after you snap the first Dugtrio.
Magnemite: Distract it with an apple.
Magneton: Force the Magnemite into a group.
Sign: Pinsir: If you release Zapdos, it will start the generator, thereby sheeding light past the articles near the Diglett. A Pinsir shadow can be seen.

Volcano Level:
Rapidash, Vulpix, Charmander, Magmar, Charmeleon, Moltres, Magikarp, Growlithe, Arcanine, Charizard
Charmeleon: You can make the Charmander evolve by causing the Magmar to attack it as it takes an apple.
Moltres: Thump the egg out of the way.
Growlithe and Arcanine: Throw Pester Balls into the craters by the exit portal.
Charizard: Thump te Charmeleon by the portal into the lava pool.
Sign: Koffing: Throw a Pester Ball into the volcano by the Rapidash.

River Level:
Poliwag, Bulbasaur, Magikarp, Slowpoke, Vileplume, Slowbro, Shellder, Cloyster, Metapod, Psyduck, Porygon, Pikachu
Vileplume: Play a song by the rafflesia flower.
Slowbro: Coax Slowpoke to the fishing spot.
Porygon: Force the terrain flaps out with a Pester Ball.
Sign: Cubone: Get Vileplume to dance, and the tree above it will become visible.

Cave Level:
Grimer, Bulbasaur, Ditto, Zubat, Muk, Jigglypuff, Koffing, Magikarp, Weepinbell, Victreebel, Pikachu, Jynx, Articuno
Muk: Snap a Grimer in the first chamber and hit a Grimer in the second with three Pester Balls.

It will evolve.
Victreebel: Knock the Weepinbell into the pool it walks around.
Articuno: Play a tune by the Jynx; the egg will hatch.
Sign: Mewtwo: Look to your left by the Weepinbell.

Valley Level:
Squirtle, Mankey, Magikarp, Goldeen, Dratini, Geodude, Sandshrew, Graveler, Sandslash, Gyarados, Staryu, Starmie, Dragonite
Sandshrew: Thump a Geodude down.
Sandslash: Thump the two Geodude down before you hit the waterfall, so they will knock the Graveler down and force the Sandslash out.
Gyarados: Knock the flipping Magikarp toward the Mankey. The Magikarp will end up by the three Graveler. Knock it into the waterfall by you and a Gyarados will emerge.
Dragonite: Throw four Pester Balls into the whirlpool.
Starmie: Snap a Staryu down the waterfall. When you come to the whirlpool, the Staryu will dive in and evolve.
Sign: Dugtrio: You see the mountain as soon as you come into the level.

Rainbow Cloud:
Mew: Knock it out of its shell and knock it again as it chases it. You'll get a great pose for it; I scored 10,000 points on that picture (no kidding)!

Well first of all there are about 63 different pokemon in pokemon snap and the harder ones are in every single level like the surfing pikachu and Scyther.