We don't know all of Mask's abilities yet b/c he's barely done anything. Who knows how this fight could go.
Current Mask is deaf meaning that James is utterly useless.
I'll side with Mask for now.
With 1 cheer; he was able to blitz and smack away two Vizard captains (one of which was in Bankai and excelled in Hakuda), giving Kensei a bloody nose. Then he proceeded to blitz Kensei again and engage in CQC with him. Presumably, he also knocked out Hisagi, Ikkaku, and the other guy out with only one cheer.
With 2 cheers; he stomped Bankai Kensei and was able to one-shot Bankai Rose with a blitz-laser that shoulda killed him.
Mask has physical power and speed plus long-range capabilities. And he hasn't even utilized his Blut capabilities yet or released his Vollstandig.
Black Star Stomps. He won't need Tsubaki.
What will cheers do? Nothing since there is no one to cheer S.
Black Star outclasses Mask in strength as well, same in durability and speed.
Untill Mask eats a nuke or fights with a broken back and arm using pure MUSCLE like Black Star did, he stands no chance.
The Masked Man takes this one. This is why I think so: He took down 5 strong soul reapers He gets stronger when James cheers him on We haven't even seen his holy form yet
Black Star can do the same. He can lolstomp Kensei and Rose.
Black Star took a nuke to his organs, was able to fight with a broken back using pure muscle, lifted thousand of tons with ease, took a laser to his eye like nothing, and has Madness Release.