Those moves are not their sigs because other Pokemon can learn them...
Mystical Fire can be learned by Mismagious, Water Shuriken can be learned by Accelgor, and Spiky Shield can be learned by Maractus/Cacturne
Greninja is now the only Pokemon with a true Signature move with Mat Block.
commented Feb 27, 2017 by Gekky
It was already stated. Though I wasn't the one who originally flagged the comment so I can't speak for the person who did flag it.