Superman is completely fair imo. He's a solid character that can scrub brush easily.
As far as spacing. Keep the perfect distance where he cannot dash up under Cupcakes and all the way to full screen. Superman cannot beat you from fullscreen like he can in other matchups. Here is an example of how hard it can be.
http://www.youtube.com/watch?feature=player_detailpage&v=TqS0SgbfQ_s&t=178
On any air dash ups try and keep in mind how good your d2 is for this. Dont be fooled by his trait. It does amazing damage but you do amazing damage the whole time! Not to mention at full screen and spacing you can trait up and possibly be SUPER HARLEY off of it.
in regards to his frame traps of F2,3 breath. You have a d1 that fits perfectly if he tries to immediatly do another F2,3. Of course this whole thing leads to a reverse mixup but just know he cant legit frame trap harley. I got more but i have work to do lol.
IN OTHER NEWS. My friend helped me figure out how much life Harley gains from the rose. 6.66%... yeah...