I think to get the TM Fly, you need to go to Solar Cave and collect some Keys. Then you get some X-Ray Specs to check each floor in Mt. Faraway (It's really useful) use the Key to get in and collect on your TM Fly, you can also get other items this way by using Selfdestruct, Explosion, or a Mobile Seed to go through walls.
Team Omni: Platinum Rank
Swampert (Leader)
Charizard
We'll catch you if you fall, we'll keep you safe, no matter what happens.