So I just used me first (by accident) against an exploding koffing, and it killed the koffing but it only hurted my xatu for what i think was the hp of the koffing (It used the current hp of the koffing to count the damage done on my xatu i think).
I figure since me first doesn't work properly yet this might be fixed when you re-code the move, so it's just a heads up :y: