Nobody could screw this up, right?
Of course someone could, and all they had to do was make the titular monsters bit players compared to the boring-ass humans that dominate the runtime. The monsters, while certainly big and bloodthirsty, regularly take a back seat to truly important matters, like Debbie Gibson talking and drinking.
"Did you hear about the Mega Shark? Let's just sit for a while and not talk about it or show it."
Gibson and her crew discover the shark and octopus frozen together in an ancient glacier, like one of those trick ice cubes with a fly stuck in it, except this is the giant kind that gods use to prank other gods.
"Seriously, take a sip of that ice water I poured you, there's nothing ... FISHY about it, I swear."
The glacier breaks open and the animals spring to life, because fuck science. If vicious brawling immediately followed, then fine. But noooooooo -- they quietly go their separate ways, because contrived human drama needs to happen. We bounce away from the newly resurrected Mega Shark and Giant Octopus and check in with Debbie, who just got fired because of an error with who gives a shit where is that Mega Shark!?!