In the reveal trailer for Nickelodeon All-Star Brawl 2, a set of gameplay footage from the first installment is shown. This is notable for two reasons, one being that the footage shows off multiple characters not featured in the second game, and that one scene shows a beta version of the Wild Waterfall stage with a smaller waterfall and different colors for the Thornberrys' ComVee. This would lead to a theory that the Wild Waterfall footage was taken from NASB 2 and accidentally inserted into the NASB 1 section of the trailer, which if true would confirm that Lincoln Loud and Leonardo were returning.

This theory was quite easily debunked by Lincoln and Leonardo using their models from the first game while everyone else got revised models, and a KO explosion effect featured in the snippet being different from one shown later in the trailer. Nigel Thornberry's character showcase would later show off a new Wild Thornberrys stage in place of Wild Waterfall, which was shortly followed by a leak showing Lincoln as an NPC cameo on the Loud Castle stage.