I want to know - it seems like a good strategy if it worked.
Thanks in advance!
as the name implies, the user of Knock Off only knocks the item off of the target's "hands".
My Aipom had Pickup and wasnt holding an item, his Ditto was holding a Life Orb, my Aipom didnt get his Life Orb.
Knock off just gets rid of the opponents item and doesn't mean that the Pokemon that knocked it off can pick it up. If you wanna do that then you can just switcheroo or trick while holding a pretty wing etc.
And btw pick up has no competitive use.
Hope I helped