Mike Mitchell (one of the directors) said this:
It's 2D and they come out of the water, and they're in our world... and there's like people out there like 'where are we?' There's SpongeBob and Patrick and Mr. Krabs... and then they find out that there's a bad guy that stole the Krabby Patty and they have to transform into life-sized superheros which is amazing... And if you can picture each one has their own superpower..."
This WILL be epic!