>>18127288While it certainly is one of the most powerful move combinations in the entire game, I feel like it takes too much time and prediction to be used effectively that often. You have to take advantage of Squidward's powerful Musician's Pride ability, which will only take effect if your opponent has a fainted Squilliam on their team (which isn't as big a problem as you'd think, since Squilliam is an OU staple). Also, Spongebob has to be in Band Forme, and you need a full HP Patrick with Mayonnaise as a held item.
It takes too much time with too little payback for my own personal taste, but if you feel you have the strategy and prediction skills to pull it off, go for it. I recommend doing it in Doubles if you do, though.
If you manage to successfully line up the moves correctly, then there is almost no doubt it's gg for your opponent.