Now to the Question

I have been tossing around the Idea of a Sailor Moon styled Chronicle but I kinda hit a snag. I am wanting the Character's to have Powers but only in their "Alternate Identities" their "Ascended" Forms as it were. How can I simulate their respective Powers only being able to be used in their Heroic Identity? I read the "Normal Identity" Flaw and while it was OK it didn't feel like it was right for what I had envisioned. HERO has a Limitations called "Only in Heroic Identity" and that was more appropriate but as I'm unsure how to use it in Mutant's and Masterminds I'm kinda hitting the proverbial wall.
I'm currently running the idea in BESM 3rd Edition, which I LOVE, but part of me wished to try it in Mutant's and Masterminds to see how it would feel.
Thank you everyone for your help.
Bows humbly
Kimura of the Fluffy Pillow