Hm... Alright Mr. D, I'll try to explain Light's powers better, or how they flow together. Right now, shes following the formula of Offense = Super Strength, Defense = Regeneration, Mobility = Kinetic Combat + Air Jump, Unique power = Atrophy, Ultimate Ability = Fusion Punch, Useless power = water breathing. Or vaguely how things worked n City of Heroes. She'd pretty much be a Street Justice(or super strength if that was possible)/Regen scrapper, if you ever remember that game.If I could state numbers, I'd have numbers set and she wouldn't look so bad.

Atrophy is more of a slow acting teleport I suppose. since its just slowly bringing whatever is affecting into the void. And Yeah, shes very difficult to kill. Not hard to knock out, but mucho difficult to kill. Just like deadpool or Wolverine. And she'll act roughly the same as Deadpool, just with less 4th walling and being more grounded. 

MC.. Well, the idea is that since he is pretty much literally living magical energy, and thus he has an exceptionally easy time learning magic, and since he sees magical energy instead of physical realm things, he can learn the intricacies of spells that way. He wont learn them right away, he'll probably have to practice them a bit and I can fix that power to be that, but thats the idea behind it. OR I could make it so that he studies the last spell used by a person and he can temporarily use that or something.

Chaos Magic is there to spice up posts. It does almost no damage, the point is to cause the other person to have to 'spice up' their post and show what their character can do/how intelligent they are. Or they can just say the chaos magic made them sneeze if they wanna cop out of it. Plus they can always dodge it. 

As for the logistics, even amateurs can make a demonic summoning circle, and said circle has a good chance of backfiring since they are amateurs, thus, easy ritual summoning of these two. As for the league, maybe I'm thinking more on the marvel side of things, but if two relatively harrmless super beings popped up that you could easily convince to fight for good, wouldn't you take that chance and scoop them up? Batman would at least. Actually... could say they appeared in gothem and that would be that. What are your ideas on that? Also I should mention that while they have combat related powers, they'll be mostly sources of comedy more than anything. After all, thats what Deadpool does :P.

And if you have problems with some powers after this, I'll change them. And for the moving around town sorta thing, I can always give MC an illusion based ability that others can use.