I don't see how Batman is a 5-5. He has so many options to get in and avoid being zoned out. Once he has bats, he can rush down Sinestro and pressure him all day. I find myself having to push-block all the time against Batman.
Catwoman and the Flash are also likely 4-6 match-ups once it gets fleshed out. They both have ways of getting in that Sinestro has no answers for. When either character is in your face, you're eating mix-up after mix-up after mix-up. One hit leads to 40% damage. I can't get enough time or space to charge trait.
I am certain Nightwing is not in Sinestro's favor. His projectile beats fear blast and rocks clean. His rush down with the staff is very hard for Sinestro to deal with.
Ares seems like a nightmare for me when I play against any competent player. They will shoot fireballs and bait your attack then teleport behind you and hit you for 45%. You can't safely zone out Ares at any place on the stage. Maybe I just don't understand the match-up, but I can't see how Sinestro mounts an offense against Ares.
Sinestro is not the kind of character that can be top 10 simply because he's always one mistake away from being in a bad situation. There are times when he can be very oppressive, but having low combo damage means one bad guess can cost you the lead and getting it back as Sinestro is very hard.
4-6 against Batgirl? How? How do you even begin to approach her? If you shoot a fireball, she teleport grabs you into a full combo. Please explain to me how you deal with this character as I probably have a 10% win rate against her and all of those wins were against REALLY bad players.
As for fighting Killer Frost.....
The only success I have is forcing Killer Frost to slide...a lot. Once I know they will be using the slide, Air Axe can lead into a full combo. This is only really possible if you keep the spacing far enough for you to react to the slide, but if you can cage them in that spot, you might be more successful.