Whats the most powerful grass,fire,and water type moves?

Question

for these 3

Answer 1

TM MOVES

Giga Impact can be learned by all three.150 Power, 90 accuracy

Hyper Beam can be learned by all three.150 Power, 90 accuracy

            MOVE TUTOR MOVES

Frenzy Plant for Serperior, 150 Power, 90 accuracy

Blast Burn for Emboar, 150 Power, 90 accuracy

Hydro Cannon for Samurott, 150 Power, 90 accuracy

                OTHER MOVES

Head Smash for Emboar, 150 Power, 80 accuracy