In Red, I mainly just use Charmeleon. I love Fire types <3
In Yellow, Pikachu, which is so duh, and Pidgeotto.
In Emerald, I mainly use Swampert and Rayquaza, but since they're level 100 already, I'm trying to train Groudon and Kyogre, but I also use Dragonite and Pikachu. I just try raising random Pokemon (like, at the moment, Butterfree and Wartortle)
In Diamond, I use Infernape and Dialga, as well as the legendary freaks (Uxie, Mesprit, Azelf) Luxray, and Steelix. I'm trying to raise Blissey, Staraptor, and Kadabra, and Feebas. If I can just see a Milotic (I know the Champion has one, thanks) I'll get the National Dex before I beat the game. And that would be awsome. Rayquaza destroying Elite Four+Champion=:3
In Pokemon Mystery Dungeon Red, mainly just Psyduck and Pikachu.
In Ranger, you can't use Pokemon like that.
And I have Pokemon Pinball R+S, but that's a special case like Ranger.
EDIT: ...You know, there's this really old thing called the "Edit" button. You should try it. It reduces spam levels, you know?