It baffles me as to why you’re not using elysion, unwanted friend is easily one if the most op moves in the game. Also, just find someone with a last biter(don penguini, godfeather, gigarock and dragaia), and you should be absolutely fine.
I made the same post some days ago. You may find many suggestions there; I made a team according to them and I easily won 
Here’s the link:
http://www.hunterislandforum.com/index.php/topic/6487-help-chapter-5-very-last-stage/#entry64834