Her passive generally clears debuffs just fine, but when she gets stunned, frozen, or teleported to the moon, her passive doesn't kick in. Now I don't know if it's intended to work this way ... But considering her power move is a pretty powerful team cleanse she works rather well as cleanser. However, you need to equip her with angels despite of her passive. Just strikes me as rather weird, but as I said, not sure if it's a bug or just another example of a not so well thought out mechanic.

The skill description reads as:
"Cleanse and Grant a Random Beneficial Effect to self or a random ally every turn"