Dodrio, a three-headed Bird Pokémon that can run faster than it can fly. Its three heads represent joy, sorrow and anger.
– Ash’s Pokedex
Dodrio is one of Gen I’s trio Pokemon (the others being Dugtrio and Magneton). But unlike the other ones, Dodrio’s heads have unique expressions. The Pokedex entry says they represent “joy, sorry and anger”, but to me, it looks like two heads are angry and like to make commotion, while the third head is either bored or guilty-looking, and pretends it doesn’t know the other two heads, haha.
Dodrio is based on the ostrich, which cannot fly, but it’s part Flying type. I guess that’s probably because the Flying type was originally the “bird” type, and it’s a bird, and it retained the Flying type (and can learn Fly) despite not having any visible wings.
Stat-wise, it has good Speed and good Attack, and it learns Drill Peck by level-up, one of the better physical Flying moves.