Your Hollow told you it was true.
Alfred got to the heart of it.
The Hollow changes what Conditions mean. They get power by re-writing their sense of self, which is a not-to-be-taken-lightly choice.
If you want to have The Hollow not walk all over you, and your name is Rudy, then give them the Condition "Rudy's bitch." They can gain power from it, yeah, but only by incorporating that power-relationship into their
sense of self. Win-win.
I don't think that The Hollow is over-powered. If anyone is overpowered, it's The Infernal. Have you
seen Strings Attached? You want a new mansion? You get it. You want a perfect girlfriend who's in perfect love with you? You get her. You want a mindless golem bodyguard? It's Free Golem Day in your neighborhood.
But, yeah. The Hollow is a weird skin with some weird mechanical tricks. But I don't really think of it as one of the "powerful" Skins. Can you share some of the situations that cropped up in your game that felt broken or weird or off-putting?