I like your idea of it being in stages for Character A Doc. And Mallet, it's definitely the "Big fans of A." They will generally be more susceptible to A, and A can't really remotely mind control them. Actually, if it's possible to simulate, it's less the "become my slave" mind control and more "Wow this person is perfect" mind control. In the sense that you'll be far more susceptible to doing what they ask you, and you'll be more inclined to follow what A says. I make the distinction because in an ideal situation, the power would still allow you some freedom of control. For example, if the character thinks doing something is in A's best interests, even though A doesn't think so, they would do it "for A's sake." I don't know how to properly model that, so I was assuming Mind Control is the simplest. The PRE attack thing seems to work better now that I think about it.
As for B, you're right. It's just a Transform power. Wow, I kind of missed that. I think the Telepathy to discover what they can change would be great. And I've already got some ideas just rereading the 6E on Transform Mind. Perhaps a No Range Requires Touch Transform will work best. I don't think B can erase power usage from their powers, though forgetting how to use your powers is possible. In that case it should just add a "Requires a Roll" limitation to the power they're "dememorizing". For hand to hand skills, should I simulate "B is taking away your memories of training" by decreasing CVs for fighting?
Also, would this be multiple transforms in a multipower? A compound power? Or a linked power for B? It seems like it should be able to do a lot, but B would have to pick what they actually want to do.