Here's the deal, for me:
Surfer, with his significantly better speed and all of his esoteric funtime good stuff would take Zamasu. Turn him into an immortal teacup - he certainly does not have anything like feats for resisting that, or acting in such a state.
Most of the class 100 brick crowd that DOESN'T have Surfer-style esoterics loses eventually, given MZ's ability to shrug or come right back from hits from SSBs.
I'm somewhat leery on Speed God Wally stealing his speed - that might be a bridge too far for me, given his specific resistance to time shenanigans and his overall power level.
It gets interesting at the skyfather level: His feats are simply not on, say, Odin level or RKT level for me. I know that some people here want to put him on "universe buster" level, but... I dunno, the feats just don't back it up, similar to how they don't for Beerus. That, and the same vulnerability to transmutation still applies.
And he's gonna get punked by anyone higher: Galactus, a Celestial, Eternity, top-level Phoenix, top-level Spectre, Franklin Richards, Lucifer Morningstar, blah blah blah.