Ghostbusters vs Kain
My attempt at humor.
The Ghostbusters get a call that Kain is wreaking havoc. The original boys don't have enough time to handle this so they call the B-List team which consists of...
Mario with a small bag of every power up he's ever had but he can only use them once.
An amalgam of TP, OOT and LTTP Link with all of the abilities and properties of the MS channeled into his Proton Pack.
Sylvanas who has an enchanted bow that can shoot arrows that have the same ghostbusting property of the packs themselves.
And they are being lead by Kirby who has his own proton pack and he has already absorbed Kain's powers because Kain did not expect such a cute little thing to be so deadly and powerful.
Before they head out they are given mental shields and blocks from Mewtwo.
For argument's sake, the energy from the proton packs can hurt Kain, but it's not something that will one shot him.