Hmm... using Jigglypuff, you should attack Giga Bowser first. Use Nap (B+Down) to knock him out with low percentage. Then, simply finish off Mewtwo and Ganondorf. Or, not so simply. Otherwise, just use your favourite character. Practice by going up against three varying difficulty Ganondorf warriors.
Edited by - No-One on Whichever day that happens to be convenient for me at Whatever time I feel like it.