I don't know when they changed the allowable amount of costumes you can have, it might of been slipped in with the last update, I've never seen it announced anywhere.
I was always worried about the limit of 200 costumes that LBP1 had as I knew I could eventually hit the limit as more DLC came out.
It was reported to be the same for LBP2, and I was told that if I wanted to save more than 200 costumes I would have to dress sackbots, save them to a Moon, then back-up that game data, then destruct the costumes to make room for others.
But as I've just been putting together the costumes from all the prize bubbles, there are 202 individual new costume parts in LBP2- 30 complete costumes self construct while completing the game, I've found I've gone over 200, and no problem, which is a very pleasant surprise.
What with all the constructed game costumes from LBP1 ported over, every DLC costume [yes I have them all ] and now the ones in LBP2, the total comes in at around 220.
Some of the new complete costumes you have to put together from LBP2 are.
Hula dancer, Belly Dancer, Scarlett, Sackbulb, Babyface, Boxer, Happy, Burlesque, Mr Moon, Mrs Sun, Nursie, Cecellia, Marie & Sacketary, and one costume that flashes called Cordless.
There might be a few more, like Andreas, Computer sack, Paperboy, Chef & tentacles costume,I'm not sure as I've still to collect 7 costume pieces, some are just one off costume pieces that don't make a character.