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.

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:

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 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.

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.

Rocko's model in Nickelodeon All-Star Brawl depicts him with underwear underneath his Hawaiian shirt, something that is not true of his standard character design in Rocko's Modern Life. This change was reverted in Nickelodeon All-Star Brawl 2 to match his original design.

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.

Out-of-bounds on Omashu are two floating textureless rectangles, while Space Madness has an out-of-bounds cube. These were both possibly used during development.

In launch versions of Nickelodeon All-Star Brawl, Garfield's stage Sweet Dreams was discovered before his official announcement in an unfinished form which takes place at day time, unlike the final version which takes place at night. Additionally, a thumbnail was discovered for an extremely early version of the stage that takes place at sunset and has an opaque lasagna tray. When Sweet Dreams returned to Nickelodeon All-Star Brawl 2, under the name Food Dream, the daytime setting for the stage would be restored.

In the final update of Nickelodeon All-Star Brawl, Patrick's command grabs gained a glitch that made them unable to penetrate through shields, negating their primary purpose. When asked about fixing Patrick's grabs after the launch of the game's sequel, gameplay and character designer Thaddeus Crews responded "I would if I could".

In 2023, a set of extremely early Nickelodeon All-Star Brawl screenshots were shared through Discord by a developer, showing an aesthetic closer to Slap City and early versions of SpongeBob, Oblina, Leonardo, The Dump, Jellyfish Fields, and - most notably - Rooftop Rumble, based on Shredder's lair from the 2012 Teenage Mutant Ninja Turtles show instead of the 80s TMNT (despite the 80s turtles having already been decided on this point). Also among the images was Hardcore Chores, Rocko's DLC stage, suggesting that a Rocko's Modern Life character may have been intended for base game.

A Twitter post made on the Nickelodeon All-Star Brawl Twitter upon the release of the Garfield DLC shows that his bib alternate costume was originally supposed to be plain white with stains of lasagna tomato sauce instead of clean with red checkers.

Nickelodeon All-Star Brawl's files have a set of unused placeholder models, all in a significantly more realistic style than the game and not based on any Nickelodeon IPs, comprised of a female pirate model from Adobe's Mixamo service; pirate, military, and ninja-themed props and weapons with unknown sources; and a "dangerous pumpkin" taken from a Unity asset store pack, which also has a leftover UI graphic alongside multiple other asset store props.

In December 2023, information spread about Warner Bros. Discovery, which owns Cartoon Network among other major animation brands, potentially merging with Paramount Global, which owns CN's long-standing TV animation rival, Nickelodeon among other animation IPs. Although this deal would not come to fruition at the time, Nickelodeon All-Star Brawl game designer Thaddeus Crews commented that he would take the chance to work on a Cartoon Network vs. Nickelodeon fighting game "in a goddamn heartbeat".

Ren & Stimpy were made a duo fighter in Nickelodeon All-Star Brawl to allow them to interact with one another, something that wouldn't be possible if they were two separate characters. Ludosity CEO Joel Nyström noted that it also allowed development time to be assigned to one extra fighter.

One divisive element of Nickelodeon All-Star Brawl is how hard it leans into competitive play, which has been perceived as coming at the detriment of content aimed at casual players such as items and a story mode. According to Ludosity CEO Joel Nyström, Nickelodeon specifically wanted the game to be able to attract a competitive audience, and chose Ludosity as a lead development team due to the positive reception of their first platform fighter, Slap City, from competitive Super Smash Bros. players. 2 years later in 2023, the game's gameplay designer and community manager Thaddeus Crews would respond to a tweet from YouTuber TierZoo complaining about a focus on complicated competitive techniques in non-Smash platform fighters, as well as some replies to the tweet complaining about 1v1-based platform fighter design as a whole, with a clarification on why Ludosity's platform fighters have been marketed so directly at competitive players, as well as why he feels other games in the subgenre are marketed as such:

Two of the first direct-feed pieces of gameplay released for Nickelodeon All-Star Brawl were a 1v1 between Nigel Thornberry and April O'Niel, and a 1v1 between CatDog and Lucy Loud. Both of these battles were wildly one-sided in favor of April and CatDog respectively. In the battle against April, Nigel was controlled by a playtester who had never actually used Nigel before; while in the battle against Lucy, CatDog was controlled by Mattias Hakulinen, who - while not a competitive player - was the best NASB player on its development team at the time. It is not known who was playing as April and Lucy.

In a sponsorship segment for Nickelodeon All-Star Brawl produced by comedy group Dude Perfect, a flat, horizontal variant of the game's logo is used on a banner. This is the only known use of this logo during the game's promotion.