Cartoon Network Punch Time Explosion XL

The Bellwood fight found in Stage 1 of the Ben 10 Theme. You need to defeat Evil Buttercup twice in under one minute. This is the strategy that worked best for me (thanks Sabre2k2!):

I kept dealing fast damage to Buttercup by pressing down and triangle to do that blue flashy move Ben does. After about 60-80 damage I begin doing his left or right plus triangle attack and it sends her flying. Hopefully with luck it makes her take a fall. Do this twice and if lucky you can beat her before the ship makes the screen flash red as by then it is already too late to get the trophy.