When the email from Nickelodeon proposing a Nicktoons platform fighter was first sent to Ludosity, the company's CEO Joel Nyström initially dismissed it as spam mail.

Originally, Reptar was going to spit cereal from his mouth, but Nickelodeon insisted that he shoot fire instead.

If the player holds the button after performing Hugh Neutron's grounded up light and then presses left or right on the stick, they can skid Hugh very slightly. Hugh moves slightly further with every skid, and, as there is no cap to how far the skids can go, he can become so fast that he teleports from one side of the stage to the other with a single skid. This has no practical use in a battle due to the amount of skids required to begin teleporting, as well as the skid count restarting every time Hugh uses the move, but appears to be a deliberate feature implemented by the developers, as every time Hugh skids, he makes a short squeaking noise.

Every single fighter intended for the base game of Nickelodeon All-Star Brawl, but not included in the reveal trailer, was leaked at some point:

• April O'Neil, Ren & Stimpy, CatDog, Aang, Korra were revealed on a silhouetted box art provided to retailers and revealed on announcement day. April's silhouette was vague enough that some people mistook her other characters, such as Carly from iCarly and the live action version of Dora the Explorer from the film Dora & the Lost City of Gold, but most fans deduced that is was April ahead of the reveal.
• Ren & Stimpy's inclusion was further proven by the discovery of an ESRB rating for the game, mentioning moves known as "Log Toss" (referencing a fictional toy from their show) and "First Fart" (referencing an episode of their show).
• A model lineup featuring Garfield was discovered from an unknown source before launch, it was confirmed to be real following the official reveal of Ren & Stimpy, whose models lined up with those featured in the leak.
• Toph was leaked by a rogue developer along with the stage line-up and scribbled out images of Garfield and Shredder. Garfield was not identified, but some players did manage to identify Shredder.
• Garfield and Shredder, who were intended for base game but had to be delayed as free DLC, were found inside the game's code through datamining immediately after launch.

Nickelodeon All-Star Brawl has an unconventional design mentality that contributed to the game's divisive reception. This was the result of the development team having very little time and resources to brainstorm due to tight deadlines, and the core gameplay implementer on the team early in development not wanting to retread their prior work on Slap City (a more conventional platform fighting game closer to the design mentality of Super Smash Bros. Melee). Community manager and game designer Thaddeus Crews noted that the absence of moves such as forward tilts, side specials, and back airs restricted what could be done with designing movesets. While he was initially upset by this, he came to accept the game's nature as it developed a small loyal fanbase, some of whom continued making unofficial patches for the game that Crews endorsed as the team was no longer allowed to continue updating the game in early 2023.

In the release version of Nickelodeon All-Star Brawl, the stage Royal Woods Cemetery from The Loud House contained a hazard where tombstones would pop out of the ground, sending any character beneath them flying and remaining as a wall for a short while afterwards. In version 1.5.0, the update that added Rocko as a playable character, this hazard was removed from the game completely, making the stage into a flat floor, similar to Final Destination from the Super Smash Bros. series. The reasoning for this change is because the stage that was intended to serve as a Final Destination parallel, Harmonic Convergence from The Legend of Korra, was considered too long for use in competitive play, and was removed from this distinction in the same update.

Nickelodeon All-Star Brawl 2 has been noted as having almost zero similarities to the game it is a sequel to from a gameplay perspective. Gameplay and moveset designer and community manager Thaddeus Crews would address this disparity in a short Twitter thread shortly after the sequel's launch by reassuring fans who prefer the first NASB that the sequel was not intended as a replacement for the first game:

Pre-release interest in Nickelodeon All-Star Brawl managed to stretch out into the Japanese Super Smash Bros. fandom, despite Nickelodeon series not being particularly popular in Japan and the channel being taken off the air in 2009. The initial popularity of the game would lead to an official Japanese release (with only in-game text being translated to Japanese) after work on the DLC was finished in 2022, something that no other Nickelodeon game by GameMill Entertainment has had, including the game's sequel. While the game's popularity would die down like it did elsewhere, steep sales and cheap discount prices would result in a regional competitive scene for the game reappearing and frequent appearances on the Nintendo Switch's sales charts. This would lead to it peaking at number #6 on Japan's Switch download charts for the entire year of 2024, beating out all of Nintendo's first-party titles on the hardware, including Super Smash Bros. Ultimate.