Before BW, I always went to League with about 4 or 5 Pokemon. I didn't like beating the League if my team wasn't full, but that happened to me frequently.
And now it's like the opposite, I get too many Pokemon before the 3rd/4th badge and I don't really like it! (Of course, they're all part of the team I want to make.) And I don't like it because I have so many Pokemon that I don't know which one I should start training first. (And because there are not lots of trainers with high-level Pokemon around.)
I'd like getting them bit by bit, but as soon as I see one of the Pokemon I want in my team, I catch it so I can start training it. It looks like in BW and B2W2, the ones I want appear early in the game, and that's why I catch them relatively soon. (Well, I must say I have traded an egg from my Black 2 to my White 2 just because I couldn't wait to get an Archen that late :P)
But eventually I manage to get them all and train them all before the League.