Unlimited Rebellion Gauge glitch
The unlimited Rebellion Gauge glitch was a glitch in Super Smash Bros. Ultimate that allowed Joker to gain Rebellion Gauge units faster in team battles involving Pokémon Trainer's Pokémon Change and Pyra and Mythra's Swap.
How to perform
To perform this glitch, the match setting must be set to team battle (the friendly fire setting does not matter). Set Joker and Pokémon Trainer on the same team. A third character should damage the Pokémon Trainer's Pokémon without KOing it until it reaches a high percentage. Then, have the Pokémon Trainer use Pokémon Change. This would cause Joker's Rebellion Gauge to fill significantly, treating the partner as if they had just taken damage. This would happen each time Pokémon Change was used, allowing Joker to summon Arsène much more quickly.
In 11.0.0 the glitch could be performed in almost the exact same way with Pokémon Trainer and Pyra/Mythra. The only difference between the previous method is that handicap must be enabled and the character that will be swapping must have their handicap set to 100% or more. The glitch will behave the same way as before, but effectively offset by 100%.
In team battles, Joker's Rebellion Gauge fills slightly when his teammates receive damage, by 0.2* the damage. Before the glitch was patched, the game registered each Pokémon character as new when brought in with Pokémon Change. So, for instance, if Squirtle was at 100% damage when switching to Ivysaur, Joker's Rebellion Gauge would fill as if Ivysaur had just taken another 100% damage, which in this case would be 20 units. 5 switches would fill the meter completely. This occurred because the Pokémon are treated like different characters, which were damaged on the frame they switched out.
In competitive play
After the glitch was discovered, teams of Joker and Pokémon Trainer were completely banned from playing in doubles due to being considered broken. A prominent incident is when MkLeo and Tweek planned to use this technique at Glitch 7 to "abuse the glitch." In response, Tantalus tweeted an announcement that the duo of Joker and Pokémon Trainer would not be legal in Glitch 7. Tantalus would have reversed the ban if Nintendo patched the glitch by a certain time frame. As of 6.0.0, this glitch was presumably patched, and so the Joker and Pokémon Trainer ban was lifted. Since the 11.0.0 method of performing the glitch required settings that aren't used in tournaments (i.e. handicap), its existence had little to no impact on competitive play.