Mega Shark has wreaked havoc in 2 previous SyFy movies (see below), but now they've built a giant robot shark to combat it! What a great idea! And Debbie Gibson is helping!
I'm not sure when this is being aired - I'm sure the information is out there somewhere but there's only so much research one can do into this subject before your one's start to bleed.
Mega Shark's first appearance was in Mega Shark Versus Giant Octopus:
And the second was in Mega Shark Vs. Crocosaurus: here's a "best parts" video clip:
More info here.