From what I remember... they give you some kinda low default types. Somebody might have to back me up on that. I actually kinda feel like pulling out my N64 today so maybe I'll go back to that one and I'll let you know. I'm pretty sure that's how it is, though. I just remember being able to get through the first quarter or so of the game with the random ones they gave me but then I started feeling like I needed more choices and higher levels.
Not to beat a dead horse... but yeah if you go to Wikipedia and look up Pokemon Stadium, I'm willing to bet it'd tell you anything you're wondering. Ditto for Battle Revolution.