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.
Explosion is not a tm so cannot be found anywhere. However a variety of Pokemon learn Explosion naturally such as Koffing, Geodude and Voltorb.
you get it at the battle subway prize stand
If you mean strongest TM, then it's Explosion (TM 64). It does 250 damage but it automatically makes your Pokemon faint.
Yawn doesn't have a TM number because it isn't a TM.
Mach Punch is not a TM so therefore it does not have a TM number.
Aura Sphere 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 prize is the TM explosion........you can also find shiny cefairys.......