The complete Pokemon Diamond and Pearl pokedex, part 3

Pokémon Name: Floatzel
Type: Water
Classification: Sea Weasel
Pokédex Number: 057 Sinnoh / 419 National
Abilities: Swift Swim – Increases speed when raining
Dream World ability: Water Veil – user cannot be burned
Useful Attacks: Ice Fang
Location Found:
D/P/P: Routes 213, 218, 221, 222, 224, 230, Fuego Ironworks, Victory Road
D/P/P/HG/SS: Evolve from Buizel
B/W: Routes 11 and 14 (via Surf, bubble spots only, rare)

When Buizel evolves, its built-in water-wings grow into a full-on innertube integrated with Floatzel's body, and it becomes significantly more powerful. In addition to better stats, Floatzel naturally learns a number of powerful and flexibles moves, such as Ice Fang for dealing with its Grass-type rivals, and the always-useful Dark attack, Crunch.

Evolution: From Buizel at level 26.