Yes, OHKO moves are able to do super effective damage (although it doesn't matter).
All OHKO have typing, so it is only natural that its super effective counterparts will apply.
"If it hits, it will inflict damage equal to the opponent's current HP, therefore knocking out the target"
With that being said, it will affect the targeted Pokemon based on their current HP, which is also why a Pokemon can Endure it or use a Focus Sash.
- 12.10.2011 3:51pm
Edit - 12.10.2011 4:03pm