Hmm, at a rough guess I wouldn't be surprised if Angelica could give the stronger MCU heroes and villains a serious fight.
She's extremely mobile with being able to fly and teleport around (if it's anything like Xigbar's teleportation in the videos i watched of his boss fight in Kingdom Hearts 2, it's got very little windup), and with portals she could probably redirect attacks (both hers that miss and even enemy attacks) away harmlessly or back into enemies. And depending on the range, she could attack from far away by opening portals right near enemies. Of course it's possible she could be attacked through the portals as well, depending on how they work.
Gravity magic has a lot of uses too, without even getting into all the normal magic she knows. Angelica can probably use it to send objects flying at enemies, send enemies themselves flying, pin enemies to the ground with crushing force, or leave them floating in the air.
Then of course she's got all the normal magic you can get in KH: so fire, ice, lightning, healing magic, and I think a couple other types off the top of my head just from what I remember from KH2. And yea, there was an MP bar that drained as you used magic in the games, so there'll be something similar to keep Angelica from casting endlessly. I'm pretty sure we'll have magical potions to recover energy and cast longer though.