In chronological order, from top to bottom
https://www.dropbox.com/s/omtg24ixrlpok ... sfrec?dl=0
https://www.dropbox.com/s/m2pk0or8l1l4l ... sfrec?dl=0
https://www.dropbox.com/s/m9nvt4wtqxzpb ... sfrec?dl=0
https://www.dropbox.com/s/19qgikvgsqapf ... sfrec?dl=0

I'm the MK, if you can, tell me what I am doing wrong and how I can improve my game.

Thanks in advance

Have you watched any of the top players like Aegis/PPStyle/DS/Dopeness/Lunary? I'd suggest if you want to get better with MK download Lunary's replay folder and watch his MK.

I only saw one replay (the 2nd one). You aren't utilizing MK's ground mobility in the neutral game. Instead, you just let your opponent approach and often times just roll or whiff grab. If you are gonna use a character like MK, its crucial to be dash dancing often in neutral for spacing, baiting, analyzing opponent patterns, etc. You also are wasting a lot of chances in your punish game. You could be following up much more instead of getting single hit smash attacks every now and then like I see you doing. Try going for safer and faster attack options that can lead to combos.