Lol @ Diddy having 3 kill moves.I think it's pretty close to even, could oscillate slightly in either direction really. Diddy has bananas while yoshi has eggs that can break your peanuts. Both can gimp each other pretty well. I have a chaingrab on you, but bananas can easily discourage that. You can deal alot of damage fast, but I can kill you at lower percentages since the only kill moves you have are fsmash, fair, and bair, (dair is rather difficult and not very trustworthy) if i recall correctly.
Besides that quick analysis, I don't know much else. I know that once you get over the initial shock of banana juggling, you don't really have too hard of a time.
More like...3 almost kill moves >_>.