In Midori's human form, he wants to get in (you know, like a grappler). But he doesn't have Rook's set of tools to accomplish that. He's also pretty slow and has a shallow jump. So you have to be pretty careful as you try to get in.
His parry is an important move. It says "hey, don't abuse me...unless you have projectiles, then go ahead and abuse me." It fails against projectiles, so he has to jump over those, or use his air C butt stomp to maneuver over them. He can also use his neutral jump, then hold forward or back and A (like Honda's floating fierce in ST). For non-projectiles though, the parry keeps people from doing too much nonsense against you. And if you land it, you get two very important powerups in addition to the 1 damage it deals. First, you get super meter (which leads to your Dragon form) and second, you enter an "empowered" state where you glow purple. In this state you AUTOMATICALLY throw anyone who is throwable. So if you're in neutral state, you don't even press any buttons and Midori will throw them. This special throw can't be yomi countered but it can be jumped out of. It's quite a threat.
Parrying fills up your meter faster, but like all characters it fills instantly if you yomi counter. So Midori's Yomi counter is the strongest in the game because his super is the slowest meter to fill otherwise.
Dragon from. Do your super (ground or air) to enter this, and you stay in it while your meter counts down. In this mode, you have several generally unfair properties. Your hitboxes being so big and high priority allow you to get in even accidental hits a lot. Your jump A is a 2-hit thing (for 2 damage!) that is one of the best moves in the game. You lose your parry, but you get the equivalent of Rook's C throw...on a RUNNING grab. Air C is a divebomb throw that only works vs grounded people. Your B torpedo attacks become even faster and higher priority and can crossup even better vs an opponent standing up from a knockdown. I think you pretty much go nuts in this mode and one way or another you can find some damage. I've generally been able to do a lot with this mode.