ralts found in route 102.
Its in the Safari Zone but i can't remeber exactly where. sorry.
You will go to Fallarbor town and go to the house south of the PokeCenter, you will find a proffessor who will trade it for a TM
TM 27 is Return.
In meteor falls, you will need waterfall to reach him. He should be between lvl 30 and 35. You will find him in the same room as the TM Dragon Claw.
you can buy TM in lilycove city like: TM 14-BLIZZARD TM 15-HYPER BEAM TM 16-LIGHT SCREEN TM 17-PROTECT TM 20-SAFE GUARD TM 25-THUNDER TM 33-REFLECT TM 38-FIRE BLAST
That is not a TM in Black
You can get the TM Psyshock in the Giant Chasm.
You have to get a tm first, than the tm case will appear in your key items pocket
I can only help you but NOT Pokemon ruby...
HM's and TM's
Endure. -Pokemon Guru