User blog comment:Pikazilla/Mewtwo vs Shadow: My Retort/@comment-32738283-20170731235125/@comment-97641-20170821152715

Considering consistent depictions of both characters in their base forms;

Shadow can be harmed by ordinary knives and bullets and finds it necessary to use ordinary guns. Basic mechs and giant aliens are considered bosses for him; and even then he wins by exploiting weakspots.

Mewtwo one-shot Onix, Alakazam, Gyarados and is considered powerful by the standards of other legendary pokemon. He singlehandedly almost defeated the entire team of the Champion Red.

The power gap is significant, and since Mewtwo has several layers of defensive options and lock-on attacks (swift, aura sphere), Shadow's speed is irrelevant. Shadow has nothing.