Body Horror: after being beaten to a pulp and stuffed into a narrow smokestack, his Healing Factor turns him into a twisted monstrosity. Later, he has to have Mighty Man break every bone in his body so they can be set properly.
Fusion Dance: the circumstances of his death result in his essence getting entangled with William Jonson's body, allowing Dragon to periodically take control, bulking Jonson up in the process.
Healing Factor: it's so powerful, he even develops immunity to mind-control.
There's a bit of Reality Ensues to go with it. Once, when severely beaten (his jaw broken, fingers mangled, among other injuries), he had to go to Mighty Man (who is a nurse in his/her civilian identity) to have his bones re-broken so they would heal correctly. So while he'll eventually recover from almost any injury, his body won't automatically just straighten everything out.
Wedding Smashers: Predictably, a bunch of villains show up and start a fight, but Ricochet yells at them and they stop. This trope was lampshaded beforehand— when Barbaric invites lots of superheroes to the wedding because he wants a big superhero wedding "like Reed and Sue", Ricochet points out how much of a disaster that was.
Missed the Call: She just happened to be the one at the deathbed of the previous Mighty Man, Robert Berman. His Grandson Billy didn't get to the hospital in time, so he transferred his powers to her instead.
Ann almost Missed The Call herself, being unaware of the transfer for weeks until she accidentally made the motion to transform into Mighty Man (striking her forearms together, while trying to break a fall). Her Savage World counterpart never had the accident, and went unknowing for years, until the Dragon from the original timeline showed her how to transform.