I think that you should replace Crawdaunt with Ferrothorn or Metagross but i think Ferro is better as it is a great wall and take down both water and ice types.Replace Dragonite with maybe a wash Rotom(You can get one in an in game trade and change it to wash rotom in shopping mall nine's store room) as it is fast with a good Sp.attack.As for Hydreigon,you need to change its moves.Replace fly with Dark pulse/Crunch and Thunder wave is good but you could change it with Surf or Draco meteor but you should go with Surf.
Here are the movesets for Ferrothorn and Wash rotom:
Ferrothorn:Seed bomb,Protect,Iron head/Gyro ball and Aerial ace
Wash rotom:Hydro pump,Thunder bolt,Volt switch and Substitute.
Hope that helped!