How do you even play against mordekaiser

In the past few months of playing League, I made several attempts to transition to top from support. This is partly due to my inexperience, but almost everytime I get matched up against Mordekaiser, and I lose. How the hell do you play against this guy? Even if you dodge his pull, his q hitbox is so big and it smacks you dead in the face anyways. You go in on him after he blows his q and pull, and he has that stupid pool around him and gains a shield. Can't win against him in his ult, let's ignore that R has like a nonexistent cooldown for how powerful it is. He feels impossible to play against early game and then he scales well later on with AP. Also he's relatively tanky. Even after I go in, his shield and pool just eats away at my health and then he pull and q is back up if I try to disengage. Can't win long fights with this guy cause of his ult, but I can't win short ones either.

[slayer-jinx-unamused]