SpongeBob's block is more of a dodge, as he crouches instead of just blocking, which he can dodge a lot of projectiles. However Patrick's (pink) and Larry's (volleyball) projectiles cannot be dodged by him.
At first, Larry the Lobster and Plankton/Robot Krabs are locked in the character selection. The only way of unlocking these two characters is by completing tournament mode.
The amusement park on Patrick's stage is the same one from "New Leaf."