Tympole, the Tadpole Pokémon. Tympole is a Water-type Pokémon and evolves into Palpitoad at level 25. Palpitoad then evolves into Seismitoad at level 36.
Black, White, Black 2, and White 2
Tympole is #535 in the National Dex, and #41 in the Unova Dex. You can catch Tympole in Pinwheel Forest in the grass in all seasons of the year in Black and White, and in Black 2 and White 2, you must first catch a Palpitoad or Seismitoad and breed it to obtain Tympole. Tympole's abilities are either Swift Swim or Hydration. Swift Swim makes Tympole's speed double when it is raining, and Hydration heals status problems of Burn, Paralysis, Poison, Sleep, or being Frozen when it is raining. Tympole's hidden ability is Water Absorb. Water Absorb recovers 25% HP when Tympole is hit by a Water-type move.
Here are more sprites and images from the games that weren't in any of the above sections.
Hope you enjoy Tympole!