To ace any level, you must complete it without dying. I would suggest looking up a walkthrough on IGN.
You ace the collector
ace the wedding of course!!
The collector in the bunker.
Complete it without dying.
You ace the 'The Wedding' levels.
you have aced it as soon as you have finished it
You have to ace the last level in LBP1.
Ace the story level: Boom Town
Lbp1: The Collector Lbp2: Negativitron
you need to ace the wedding reception so complete it with out dieing.
You have to ace the three Savannah levels to get the full costume
You get it in DLC Celebration pack