Unfortunately I have not watched the anime, so can't help with personality matchups.
Just from what I read on the fandom wiki it sounds like protection (for others) is the most likely of mtg mechanics she would have.
Mother of Runes,
Eight-and-a-Half-Tails.
I noticed that she summons guns, so I'm thinking creatures that search for equipment.
Stoneforge Mystic seems the best as you can then tap to "pull those weapons out".
It says she has several weapons in her arsenal so you could play some equipment that represents them.
I'm not to sure what going to best represent her weapons but
Umezawa's Jitte using the -1/-1 sort of like firing a rifle (you know shooting at a distance).
Assimilation Aegis could represent a one-use of a weapon -or- restraint magic.
Sword of Truth and Justice "helping" other creatures with buffs.
Anyway if you like this idea, more thought could be put into equipment that represent her arsenal.
The other thing I read was about her transformation into Holy Mami. I was thinking literally transform cards.
Kytheon, Hero of Akros is one. The transformed side does give other creatures indestructible for a turn.
The other one is
Urza, Lord Protector (it has protector in the name!) and meld with
The Mightstone and Weakstone.
Urza, Planeswalker would be her "Holy Mami" form and
The Mightstone and Weakstone could represent her soul gem.
That's kind of nice that you have to wait for both of them, as story wise her transformation wouldn't happen until further into a game.