Mask Man's power is the ability to copy people's forms and powers with masks, he can only control dolls when he copies Doll Master. Just think of him as Evil Megaman. Doll Master was the one who can control dolls exclusively, and then we killed her.
Also going to look up some other non Kingdom Hearts tracks, I like Kingdom Hearts music quite a bit but I prefer other things for boss music. I don't know why but I just don't really care too much for the boss music, maybe it's because of the instruments? I mean I like everything else, from the over world and random encounter battle music, but boss music is a hit or miss to me. The boss music just mehs me and I don't know why exactly.
Maybe a remix of the Magus boss fight in Chrono Trigger would be good for Mask Master.
EDIT: Oh and what do you know found it on the first try.
Epic Magus Battle Orchestral Chrono Trigger RemixOr this one which is more bombastic, shorter and doesn't have the laughing sound effect.
Battle With Magus - Chrono Resurrection Version by tssfNow I'm going to look at Radient Historia, Bravely Default, and Xenoblade music.