the most powerful physic move is Psycho Boost
The most powerful normal type move is Giga Impact
The most powerful rock type move is either rock wrecker and head smash
insidious
Psychic.
In terms of base power, the most powerful move is explosion, then self destruct, but they both cause you to faint after using them.
hydro pump
Magma Storm
Its eruption as the first powerful is blast burn.
Frenzy Plant
Psystrike
The most powerful move is frenzy plant. Only the grass type starters of each region can learn it from a guy on route 228.
The most powerful dragon move is roar of time which can only be learned by dialga. otherwise it's Draco meteor