Question

i mean what are the chances of a powerfull move from metronome

Answer 1

There are 559 moves in total. 40 moves cannot be selected. I'm going to assume powerful moves are base 100 power and up:
77.

77 / 519.

Comments

There is 559 moves.

http://bulbapedia.bulbagarden.net/wiki/Moves#Characteristics_of_moves

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I messed up. I read somewhere else that is was 420...