Why not use Thunder Fang? deals with Water and Flying types well, especially Gyarados, you just need to go to the Move Re-learner in Pastoria to have Houndoom learn it.
NOWMYME NOW MYME NOW MIME Now Mime!!! :o They're conspiring against me! :shock: You should move this to the General Guides forum it would be better suited there. Also how long does it take for a tree to go from stage 1 to a full grown tree?