You basically cannot make a single unforced error. Mew2king does not make many commitments. His spacing simply adjusts based on what he thinks you will do and if you do it, you'll be punished hard, and if you didn't do what he expected, well he didn't really risk anything to begin with. It's a play style that lets him both stay safe and hold you accountable for any misstep you make.
Take for example playing Falco against his Marth. He will almost always be spaced away so that it appears you can short hop nair/dair at him, but if you try, he will dash away and pivot grab you. Once you stop recklessly approaching him, he might do a few other things, but mostly you will see the decisions in how he positions his character, not in the attacks he throws out.
He wins via his excellent spacing game. Give him excellent fake-outs in quick succession so that he can't accommodate for everything, then he might just need to take a chance. Much harder said then done though, and maybe I'm just not good enough to see what he has in store for people who can keep up with his spacing.