Especially not one as on the wrong side of the law as Waternoose, lol!
You’re exactly right there- the one thing all of these myths and ‘sightings’ of strange creatures have in common are that the creatures do always seem very suited to their environment.
I guess with Mike and Sulley banishing Randall to a swamp through a house, (or, rather, a trailer) maybe they just didn’t know any of the banishment door codes. I can imagine them, after having caught Randall, opening a few doors to find one suitable- one that doesn’t lead to anywhere else so Randall wouldn’t be able to return immediately- and then deciding that a swamp would be a good idea, especially since Randall seems suited to that sort of environment (though in reality, he probably wasn’t).
The only problem with that theory is that it implies that unless Mike and Sulley actually went into the trailer, then outside into the Human World to actually see what the environment was like, they wouldn’t have realised that the trailer was situated in a swamp- why should it be? I guess they could’ve quickly looked out of one of the windows or something, but the way they banished Randall made it look like they themselves had never entered the door in the first place, and were just chucking Randall through it.
It also could’ve just been a lucky pick!
But now I’m diverging from the original topic. So, back on topic, I still think that Waternoose could easily have been the cause for some, if not all the banishments mentioned- Big Foot, the Yeti, etc.
I’m also going to nitpick that idea- if Waternoose privately banished them because they did something wrong in his grand scheme, why would anyone else know about it? And therefore, why would Mike say what he said in the film about these banished monsters? If Waternoose had done it himself, then he might’ve started off a rumour that Big Foot or Yeti had just gone missing randomly or something, since banishment without consent is surely an illegal activity, and this would turn the trail away from him. Therefore, the banishments must’ve been official, performed by the proper authorities, so my idea doesn’t stack up.