Trade.
There is not a tm for bite or crunch.
Thunderbolt
Yes, Tm's in Pokemon Omega Ruby and Alpha Sapphire are re-useable
Double Team
you can get it in seafloor cavern
25
In ruby ,sapphire, and emerald you can get TM 50 by beating the fourth gym leader just in case you don't know what TM 50 is it's overheat.
at the game corner
In the Safari Zone
double team
Location is Route 115
It is located at Meteor Falls