Cartoon Network Punch Time Explosion XL

You first need to buy Aku from the store for 1500 points. (On Easy) Go to Story Mode - Level Select - Samurai Jack Theme Stage 4. Choose Aku as your main character (it doesn't matter who the other 3 are). 30 Enemies will spawn. Keep jumping over them and dodging their attacks and go only for the assists blocks. Keep getting them until Aku's Synergy Assist (Rockstar) activates. If he kills two enemies while he's up (most likely will), the trophy pop.