I personally feel as long as you space well, MK is easy. No matter what character you are.
I beat a good MK with my PT because of spacing and teching (and Luigi's Mansion is made of win)
It's the fact that everyone is focused on how fast MK is, and high priority (aka, speed and disjointed) his attacks are. That they don't bother looking at his major weaknesses.
He's -forced- to approach, and 90% of the time its with a SH'd aerial.. :| (I've faced good MK's, I've been 3 stocked by good MK's, that doesn't mean hes broken, it means the other player is a greater level then myself)