Knock Off doesn't work as supposed to when it's used again a pokemon which is holding a berry.
Testing situation:
LVL 100 Krookodile with Knock Off against LVL25 Sturdy Golem which is holding a Sitrus Berry.
Krookodile uses Knock Off on Golem, Golem sturdy activates and the berry gets Knocked Off as supposed to but the Golem still regains some HP thanks to the berry effect.
This isn't supposed to happen because after Knocking off the item (in this case the berry) you shouldn't get the item effect anymore.
I think there's also something suspicious about the damage reducing berries.
Colbur Berry doesn't seem to work when a pokemon uses Knock Off on a pokemon holding it.
~ Xasah