The Rebellion Gauge is a gray meter with a black frame, which is present next to Joker's portrait at all times. By default, it has a red splash around it, but if the match is in Mementos and Persona 3 or Persona 4 music is playing, the splash's color changes to blue or yellow, respectively. As the Rebellion Gauge fills, the gray is replaced with pink.
The Rebellion Gauge slowly fills over time, but can be more efficiently filled by (in increasing order of effectiveness): one of Joker's teammates being KO'd, one of Joker's teammates being attacked, Joker himself being attacked (which causes a spark matching the color of the splash at the right end of the Gauge), and Joker being attacked while using Rebel's Guard.
When the meter is filled, Arsène is summoned and the Rebellion Gauge turns cyan with blue flames behind it. Joker’s mask also disappears while the Rebellion Gauge is in effect. Arsène remains active to boost Joker's abilities until the Rebellion Gauge runs out, which takes 30 seconds. Taking damage causes larger portions to be removed. Once the Rebellion Gauge depletes fully, Arsène leaves Joker and the meter resets to its default state. Joker is invincible during the animations in which Arsène is summoned and when he leaves. Several instances can temporarily halt the depletion of the activated Rebellion Gauge. These include:
- Joker getting stunned:
- Joker falling asleep.
- Entering any cannon, such as:
- Getting trapped in a barrel in Wrecking Crew.
- Using a Bullet Bill.
- Another player landing a cutscene Final Smash, such as Stampede! or Blue Falcon. This applies even if Joker is caught in the move, although damage taken will still reduce his Rebellion Gauge.
In Home Run Contest, the Rebellion Gauge starts out full and does not deplete, and Arsène will always be active.
When Arsène is active, his hitboxes are added to almost all of Joker's standard attacks, with the exception of his pummel, throws, and floor and edge attacks. Arsène's hitboxes have a part of 1, meaning that they can hit simultaneously with Joker's own hitboxes. When Arsène is active, Joker's own hitboxes deal the same damage as when he is not present, but might have other properties like size, knockback or angles changed. During this state, Joker is colloquially referred to as Awakened Joker. Curiously, if Arséne vanishes while Joker is performing an attack, the Awakened values will apply until the attack animation ends.
The Rebellion Gauge fills in units, calculated by 1.3 * the damage Joker receives throughout the battle if he is hit. For example, a move dealing 3% will fill the gauge by 3.9 units. Taking around 76.92% (the actual calculation for this, 100 divided by 1.3, results in a very long number) will give enough units for Arsène every time. It will also passively generate units, at 0.00925 per Frame. In a more readable format, it fills at 1.11 units every 2 seconds; after 3 minutes spent without taking any damage, Joker will automatically summon Arsène. This also applies to teammates, although it is filled by 0.2* the result. If Joker uses Rebel's Guard, the gauge will fill by 1.3 * 0.4 * 6.7368 * the damage taken, instantly filling it after taking 28.6% damage or more. 
When the Rebellion Gauge reaches 100 Units, Arsène will appear for 30 seconds, or 1800 frames. If Joker is hit during this time period, the Rebellion Gauge will decrease by 16 * the damage received, provided two or three players are present, only this time in frames rather than units (to calculate in seconds, divide the result by 60). A move dealing 15% in an 1v1 battle will subtract 240 frames, or 4 seconds, from the Rebellion Gauge. Depending from the number of players in a match, the multiplier for the depletion of the Rebellion Gauge changes; it will use a 10.2 multiplier for a 4 players match, 8.6 for 5 players, 7.8 for 6 players, 7 for 7 players and 6.3 for 8 players. 
All calculations involving the Rebellion Gauge will take the 1v1 multiplier and other damage multipliers into account.
If Joker is KO'd at any point, the meter will reset at 20 units regardless of how filled it was beforehand. If Joker is behind in stocks, the gauge will fill at a faster rate. However, the specifics for this are still unknown. 
|Move List||Joker's Rebellion Gauge will fill if he is hit while using his down special and when he takes damage in general. When the gauge is full, Joker will summon Arsene, who strengthens his attacks and changes his special moves. The Rebellion Gauge also fills slowly over time.|
The Rebellion Gauge is functionally unique to Super Smash Bros.; in the Persona series, Personas could be summoned at will after their user has awakened them so long as the user has enough SP to spend for the selected attack, said SP functioning as it usually does in role-playing games. It has been theorized that the mechanic of the Rebellion Gauge is instead meant to invoke the process of awakening one's Persona, which in Persona 5 came from finding resolve in the face of extreme hardship. Thus, being on the defensive through most of the match could be seen as evocative of said moment, while Arsène appearing to grant Joker the power needed to turn the tide in his favor is evocative of him gaining the resolve to triumph over it.
When Arsène is active, the Rebellion Gauge's color fittingly matches that of the HP gauge in Persona 5. Otherwise, it matches the color of the SP gauge.
- If Joker is in Training Mode, increasing his damage percentage through the menu has an immediate effect on his Rebellion Gauge. This can be most easily noticed by setting his damage from 0% to 999%, in which case his Rebellion Gauge will fill or empty instantly. Decreasing his damage has no effect.
- Prior to 6.0.0, if Joker and Pokémon Trainer were on the same team and the Pokémon Trainer switched Pokémon after being damaged, the Rebellion Gauge would receive a substantial boost in meter. This occurred because the game believed that the switched Pokémon was a new character, and filled the meter in order to compensate. This technique has been banned by many tournaments in doubles. This was reintroduced into the game with the addition of Pyra and Mythra, but only works with a damage handicap of at least 100%.