lol this is supposed to be a real tough match up, but i play with a really good MK all the time so ive managed to learn how to play them. ur Dtilt and Utilt both out prioritize MK's tornado, aaaand on top of that the Utilt kills metaknight at 91%. Tech chase using ur Dthrow and if they ever roll towards you, dsmash them, and that move usually kills at around 110%. Space yourself using a lot of Ftilts and Dtilts when MK tries to rush you. Lots of bairs fairs and throw some waddles into the mix when edgeguarding. Oh and at the edge of most maps (fd, battlefield, yoshies island etc.) you can kill metaknight using a Bthrow at around 136% or so, but they should be killed by a bair or a Utilt before you should have to resort to that