What it says on the tin!
My favorite Pokémon used to be Noivern because he's so big and so cool and if Pokémon were real, I could fly on his back... but then Sun and Moon came out and Salandit appeared. He's perfect, just a little guy (we don't mention the evolution) He's scratchy and squiggly and, again, just a little guy.
What's your favorite Pokémon?