I actually really like the idea of Splaat (Klasky Csupo logo) in NASB - he's a memorable character to 90s and 2000s-era Nicktoon fans, and he's managed to gain an inexplacable but quite clever cult following with the current day Nickelodeon kid audience. I feel his moveset could, just as Hugh seems to play into his memes, play into the Klasky Csupo memes by giving him wacky logo effects to fight with.
Another NASB character idea I like is Swiper, a good way to rep Nick Jr. without turning a preschool role model into a combatant, given he's a villain and all - he could still have the fake interactivity represented, and I feel his inclusion would probably appeal to Nick's core demo more than Dora herself because: let's face it, 6-to-12 year old kids love making fun of "baby shows", and one of the quintessential outlets for that is cheering on the antagonistic character. Mayor Humdinger (is that his name?) could also work for this to a lesser extent, but he wouldn't really appeal to NASB's nostalgic core demo like Swiper would.