One of the products I very much like is the Iconic Legends series from Rogue Genius Games, which are ICONS versions of various comic characters with new names and backstories. (Jacob Blackmon and Mike Lafferty do the writing and co-creation.) It's an excellent series.
Anyway, to me, it seems that the biggest problem is that the characters in the series might overshadow the PCs. (Whether they do or not depends on your campaign or whether these characters are being played.) My proposed way to handle this is Fallen Icons: characters who cannot fight crime any more, but who obviously were closely modeled on existing characters. A second note talks about what needs to be changed to make them characters in their prime (or if those are extensive, a whole second character—it's ICONS; that won't be huge).
For whatever reason, all of the characters that RGG has released so far have Marvel characters are their inspirations; to avoid stepping on toes, I'll do DC characters. Here's one.
Big BrotherGrim Justice (Spencer Fade) was one of the great trained heroes the world had seen, but even with the incredible good luck that some heroes have, a trained hero has a limited shelf life. Eventually, an augmented individual named Blight was as smart as he was, and stronger. After some years of crime fighting, Spencer Fade escaped with a broken back, paralyzed from the hips down.
After a long and ultimately fruitless search for a cure, he switched tactics. He became Big Brother, the all-seeing information broker and aid to heroes everywhere.
One of his temporary solutions has been built into his wheelchair. The powered exoskeleton which he hoped would replace his legs has been built into his chair. Should an old enemy discover his identity, the chair unfolds legs and has enough power to let him function briefly, usually enough time to get away. There are also some weapons built into the chair so he can protect the bystanders who are there. He may have to succumb to his enemies—the Grimace, Blight, Quizzical, Bubastis, and others—but he doesn't plan to make it easy.
|Athletics, Investigation, Martial Arts Expert, Technology, Weapons (in wheelchair) Master|
|3||Blast (hidden device in wheelchair)|
|4||Gadgets (in wheelchair)|
|4||Leaping (wheelchair unfolds into exoskeleton) Limit: Temporary|
|Extra: Super Speed (Wheelchair/exoskeleton is motorized) Limit: Temporary|
|Big Brother Sees All But Can't Walk|
|Justice is a Harsh Mistress|
|Old Enemies and Allies|
Grim JusticeIn his prime, his powers looked like this:
|Coordination was 6|
|The Weapons specialty was Weapons (thrown), but only as a specialist.|
|3||Blast (Device: thrown baton)|
|5||Swinging (Device: Swingline)|
|3||Gadgets (Device: Utility belt) including Life Support, cameras, pocket crime lab, etc.|
|Instead of the Big Brother quality, he had "Billionaire playboy and philanthropist"|
The original comics character is hard to convert: over his decades-long history he's been everything from grim avenger in the night to jolly costumed cop. So I picked and chose. You might have a separate interpretation, and it's perfectly valid.