These guys. I think they haven't been getting enough love recently. I've seen people move them to mid-tier, even low mid-tier. I'd say they're high-mid tier at the lowest.
Pros:
Heavy while in kart, hard to knock around
Fairly fast approaches with kart
Nice projectile and melee options
Nice stops in Dtilt, dash attack and B
Tool-chests on tool-chests
Couple of reliable combos (SideB into Uair/Dair) (UpB explosion into Fair hammer)
Kart defense
Dtilt as a taunt
Cons:
Out-of-Kart vulnerability
Slowish attacks, broadcast kart startup
What are Koopa Jay's other weaknesses? I know they're there, just like everyone else's, but why does he keep getting moved down?