I'd say it looks like Marf, but they have some issues with getting antsy, and both are ***** by MK, so I suppose not...
Yoshi? Yoshi is just really strong in doubles. He's a tank if there isn't a Cape on the map, and he can carry in a 1v2 if the user's got game. Fills that killing power gap pretty fine.
I bet there's a ton of **** traps. Pit's hits are really obvious for the Yoshi to notice - "Yoshi can hitconfirm Pit's moves" - and Yoshi is really annoying when he's in your face, letting Pit breathe and position. Between them the DPS could skyrocket.
They both have resiliency on their own for sufficiently good users so no one has to babysit, and there's so much room for invention, starting with their projectiles.
Consider this: Shield pressure to Yoshi bomb. Yoshi throw to Pit juggle to offstage. Anything -> Yoshi aerial. Yoshi BAir -> Whatever the **** you want, get a coffee, unplug play Ganon land Murder Punch punish = D3's dash attack, come back, Fsmash. Arrow of Light -> Yoshi not being pressured in his craptastic shield egg, Pit gets launched, DIs, is safe. Egg Lay -> Pit move refresh.
As a more subtle point to saying "Pit wants people who kill", I think Pit wants people who can move - no, PLOW the game toward its conclusion. Pit plays a campy game at his height in 1v1, supposedly showing off his strength, but really a symptom of his discomfort with any other speed or rhythm of play. Discomfort with only himself to control space... which he's actually really bad at (if they're too close for arrow, right?)
But with some character (like Yoshi!) out there smacking everyone around, moving the game along, Pit can take on just what he can carry - but pay strong returns, too. He's not just using a stronger ally; the support enables him to do what Pit mains (and the SBR, tentatively, but persistingly) are so sure Pit has within him.
I'd learn Yoshi if I was manly enough to play the critter.
Right? I mean, along the lines of how Peach, say, would be a bad fit.... both chars would be working so hard to not insta-die, and set up their ideal situation, and they'd sputter because a rival will always screw you up once, and it'd be ugly. But maybe a super aggro Pikachu would be a good fit.
Extending this:
Dedede: Bad
Wario: Probly good
Game & Watch: bad <- I guess? He might not be able to satisfy the above conditions depending on opponent characters, but the payoff of his moves is SO GOOD for his weight class
Robot: good (despite being a sandbag at the worst of times)
You feel me?
. Btw our main competition is a fairly competent snake and his partner who is debatably the best Link main in the world. I swear to God if anyone asks if the Link main is Izaw I will blow a fuse. 
