While I would certainly say it's unlikely I couldn't out right say no chance or impossible.
With guys like Inky, Blinky and so on serving like 3 different roles in the game that tells me there is no hard rule about who does or can do what. They are attacks, back ground hazards and assist trophies all roled into one.
DK is also a hazard on 75 Meters. Now I know people say that's Cranky, but for all intents and purposes it's Donkey Kong, just look at he promotional art for Pac Man or even Duck Hunt Dogs intro movie, DK is DK. I suppose if you really want to stretch it, Cranky Kong turns into Donkey Kong during Duck Hunts movie.
Then not to mention Duck Hunt dog and the ducks themselves, the are back ground elements that can affect players, 2D art style or not, it's them with multiple roles.
Again I'm not saying it's likely for hazards or assists to become playable but I think my examples justify why it's not a hard rule saying they cant.