Here’s some background info on Butterball: https://superhuman-characters-and-their-powers.fandom.com/wiki/Butterball_(Marvel_Comics)
He’s impervious to all physical damage, but is actually just an average man on offense.
Round 1: He joins the crew on Titan, can they get the Infinity Gauntlet off Thanos?
Round 2: He joins the group in Wakanda for the final fight, do the results change from the movie in any way?
The only way I can see him adding much is if Rocker is able to give him a weapon, otherwise he’s just a guy with… A sword? A gun?