Hyper beam.
No, Butterfree cannot learn Fly.
NO!
Hydro Cannon
It can't learn fly
Pidgeot is a Flying type and the strongest Flying type move it can learn is Sky Attack.
i think the strongest move is flare blitz
HM 2, which is Fly, cannot be taught to Butterfree.
yes, it does
Butterfree can't learn Aerial Ace by level up. It can, however, learn it by TM, which you can find on Route 9.
Butterfree learns confusion at level 12.
Butterfree learns Confusion as it's first move. Lv. 10. If you for some reason do not have the movie in a Butterfree of higher lv. simply either breed a new Caterpie or visit the move re-learner in his house on Island Two for him to teach it the move again (costs either 1 Big Mushroom or 2 TinyMushrooms).
14