Miltank, the Milk Cow Pokémon. Miltank produces very nutritious milk, a perfect drink for reviving sick Pokémon. Miltank are very even tempered and prefer not to battle.
– Ash’s Pokedex
Miltank is based on a cow. It still has no evolutionary relatives. I think there should be a pre-evolution of Miltank, based on a calf, where if female, evolves into Miltank, and if male, evolves into Tauros (which also currently has no evolutionary relatives).
Stat-wise, Miltank is actually pretty good; it has lots of Speed and Defense (highest of non-legendary Normal type Pokemon), and decent Attack and HP. But I think it’s more commonly used as a Defensive Pokemon (as Ash’s Pokedex entry suggests).
Many of Miltank’s Pokedex entries speak of humans drinking Miltank’s milk (Moomoo Milk). I think this is one of the few instances in Pokemon where it suggests humans consume something produced from Pokemon. (are Pokemon eaten? we’re not sure).
Moomoo milk is awesome though. It heals 100 HP, and is relatively cheap (cheaper than potions by ratio of price to amount of HP healed). Miltank’s signature move, Milk Drink, can be used in the field to heal other Pokemon in your party.