You get what you pay for.
I don’t know when exactly the whole “so bad it’s good” craze infiltrated the mainstream movie-going public, but lately we’ve gotten dozens of cheap, z-grade entertainment made and sold for the sole reason to be enjoyed ironically. Which is a problem: what made movies such as Plan 9 from Outer Space enjoyable was their sincerity - the filmmakers were genuinely trying to make scary or dramatic films. When a film like Sharknado is made as a joke, it loses that special something that made older B-movies fun to watch. And thus we have Monster Brawl, a joyless and derivative slugfest that can barely even muster up any fun in a werewolf vs. the Frankenstein monster (which the film rather dumbly refers to simply as "Frankenstein") fight. There’s no real script - the film is presented as something of a very special episode of WWE, with a host of monsters facing off against each other while horribly-acted announcers provide color commentary. You can see how a great cult movie could come out of the concept - perhaps with some Verhoeven-esque satire of reality TV and the pro-wrestling biz, but Monster Brawl features no originality or spark whatsoever. You’d think the filmmakers could have at least made the actual brawls themselves fun to watch, but it’s just a bunch of folks in rubber suits play-acting in a wrestling ring. It’s a movie made because the central concept will sell to its targeted audience, and not be questioned over its poor quality because, hey! It's supposed to be "bad" on purpose.