Explosion is TM 64
This should help... TM 64 (Explosion) - Buy Ragecandybar at Mahogany, exchange with guy in underground path between Cerulean and Vermillion
You get the TM Explosion from Veilstone City Game Corner EDIT (by venom phoenix): more than that, you have to get 10 extra rounds in a bonus round. its based purely on luck.
Yawn doesn't have a TM number because it isn't a TM.
you get it at the battle subway prize stand
Explosion is not a tm so cannot be found anywhere. However a variety of Pokemon learn Explosion naturally such as Koffing, Geodude and Voltorb.
If you mean strongest TM, then it's Explosion (TM 64). It does 250 damage but it automatically makes your Pokemon faint.
Aura Sphere is not a TM so therefore it does not have a TM number.
Mach Punch is not a TM so therefore it does not have a TM number.
you can give it to a in an underground tunnel in kanto and he will give you the TM for explosion
In the forbiden forest under your shoulder.
it is TM number 43
the TM dig is number 28