When they vibrate the bumps on their heads, they can make waves in water or earthquake-like vibrations on land.
– Pokemon Black Pokedex
Palpitoad is Gen V’s Water/Ground Pokemon (there has been at least one per Gen since Gen II). It’s based on a toad that lives in the swamp. It can learn many attacks based on sound; it’s one of the few Pokemon that learns Round (a new Gen V move) by level-up. Despite its Pokedex entries saying how it can make earthquake-like vibrations on land, and it being part Ground, it can’t learn Earthquake (not by level-up nor TM). It has to evolve into Seismitoad before it can learn Earthquake (by TM only).
Stat-wise, Palpitoad’s stats are rather evenly spread. Its Sp Attack and Attack are the same, so it can be a mixed attacker.