Let's consider the world-building. A corporation can sponsor or employ a superhero because it created the hero, so it can work in a world with very few heroes and villains. (That would actually work for a three-heroes-and-no-supervillains background, right up until the rise of, well, supervillains.) In that case, the superheroes are probably transformed humans, gadget-based humans, or artificial in some way, but aliens aren't impossible.
On the other hand, maybe there are so many superpowered people that the corporation sees an advantage in having one. Evil Faceless Corporation (henceforth EFC) looks much more caring if Captain Compassion is on the job. (They just have to keep him out of Houston, where they're doing something...and that's just a name I picked out of a hat, not a reference to any real world thing.)
If most of the superpowered people don't actually want to be heroes or villains then the corporate sponsorship is opportunistic and possibly unhindered by a moral code.
So corporate sponsorship can work with almost any number of super-powered folks, but the fewer there are, the more you have to justify it.
There are a couple of variations on the corporate superhero:
- The hero has no powers or abilities at all, even in costume, but any acts of "heroism" are carefully stage-managed to look like such. In this case, the company gets the good will engendered by a "hero." It's probably cheaper to create a faux hero this way, but not cheaper to maintain this facade. Useful primarily as part of some other scheme (though a "keeping up with the Joneses" competitive matching scheme might work: if every other corporation in your market segment has a superhero and you don't, it might be worth it).
- The hero has abilities, but acts of heroism are stage-managed to get a better effect. I'm not sure where stage-management shades into support staff, and you might be able to play with that distinction, especially if your heroes have a support staff.
- The hero is meant for something else (such as advertisement or promotion) and stumbles into the heroism thing, to the delight or chagrin of his or her handlers. "We were fine when you got the cat out of the tree, but a guy who flies and is not bullet-proof should not be stopping bank robberies, he should just be tailing the criminals." This is a broader definition of the Tony Stark cover story that Iron Man is the bodyguard. It includes bodyguards but also the guy who makes supermarket appearances, or who acts as a superfast courier.
- The hero is actually a hero, paid for by the company. The hero gets to hero without money worries, while the company gets reflected glory and good will. Expect pushback if the hero investigates corruption in a corporation or conflicts with their market segment.
- The hero is actually a hero and is accepting sponsorship, which might lead to a conflict of interest when they tell the hero to look in one direction while they do something else.
- The hero is totally on board with this and is maximizing profit. In stories, this character and the character in the item before are probably bad, but it might be more interesting to have them simply choose to help in the areas that don't leave them open to a conflict of interest, and to emphasize the ways in which that makes them similar to the player characters.
- The corporation makes the heroes and funds them, but really makes its money on marketing their images (which is, I think, part of the background of Seana McGuire's Velveteen stories). The heroism thing is a loss-leader: it's necessary to keep the marketing going (you have to have something to market) but they aren't going to pour an infinite amount of money into it, either. It's possible that the corporate heroes are opposed by villains who are also funded by the corporation, that the stories (like professional wrestling) are planned out in advance but loosely, allowing for change depending on what happens.
A team of corporate heroes could be interesting rivals or opponents for the heroes without actually being bad.