Rematch

Rematch is a feature added to the Spirit List in version 8.0.0 of Super Smash Bros. Ultimate. Unlocking the spirit the first time will allow them to be viewed in the Spirit List, where they can be rematched as many times as one desires. Spirits that can be fought have a red label with the Spirits logo on it and can be rematched by pressing either the X or + button. The rematch battles are set up as if they were on the Spirit Board, including allowing the usage of Support Items. Any spirit with a battle can be rematched in this mode, even those whose battles are not normally accessible through the Spirit Board (for example, master spirits whose battles are normally exclusive to Adventure Mode: World of Light). Spirits that belong to a Challenger Pack and are purchased from the Vault Shop will require their respective Challenger Pack to be purchased in order to be rematched. Some select spirits do not have a red label, and thus are not allowed to be rematched. The vast majority of these unlabeled spirits do not have an accompanying spirit battle, i.e. fighter spirits, upgradeable spirits, and spirits only obtainable through summoning or shopping.

After beating the spirit in the battle, the player will gain a high score, SP, experience, and the spirit icon will be darkened. This, however, will not award additional copies of the spirit,, Snacks, or any Support Items. Once defeated, a score is seen in the top right of the screen (under the number of spirits obtained) that accumulates with every Spirit Battle won, up to a maximum of 600,470,000 as of version 13.0.1. Similar to collecting every spirit, there is no special reward or congratulations screen for clearing or getting the max score for every rematch.

The score obtained is determined by the player's team power, with the highest possible score being the Spirit Battle's power times 100 and the lowest score being the Spirit Battle's power. The amount of SP earned can be determined by the primary spirit's power and the number of players.

Data
The formula for the score gained is floor(b × (0.16r² - 0.8r + 1) × i) × 100, where r is less than or equal to 2.25. An r of 0 (i.e. no spirit team) will give a score of b × 100, and an r of 2.25 will give a score of b. The final value will never be lower than b, even if r is 2.25 and a Battle Item is used.
 * b is the opponent's battle power.
 * r is the player's team power divided by the opponent's battle power. The player's team power includes traits, skills, and the 10% series bonus but not styles.
 * i is a 0.95× multiplier applied if a Battle Item is used.

The formula for the SP rewarded is floor( ((c / 1000000) × (b - p)² + o) × (1 + (n / n_s)) ) × 10. When playing solo with no spirit team the formula can be simplified to floor( ((c / 1000000) × b² + o) ) × 10. The minimum amount that can be rewarded is 100 SP. Master spirits have an upper limit of 1250 SP, preventing large amounts of SP being gained due to their steep curve.
 * b is the opponent's battle power.
 * p is the player's primary spirit's power. This includes the 10% series bonus as the spirit's stats are directly modified.
 * c is a value dependent on the opponent's class:
 * p ≤ b:
 * c = 8.00, ★☆☆☆ Novice/Master
 * c = 4.00, ★★☆☆ Advanced
 * c = 2.75, ★★★☆ Ace
 * c = 2.25, ★★★★ Legend
 * p > b:
 * c = -5.00
 * n and n_s are used when multiple players participate:
 * n:
 * n = .10, ★☆☆☆ Novice/Master
 * n = .14, ★★☆☆ Advanced
 * n = .18, ★★★☆ Ace
 * n = .22, ★★★★ Legend
 * n_s:
 * n_s = 2.0, 2 players
 * n_s = 1.3, 3 players
 * n_s = 1.0, 4 players
 * o is an offset with the formula (0.00000395b² - 0.0095b + 100) / 3.66.

Trivia

 * During Spirit Board events that offer rewards for beating any spirit on the Spirit Board, winning a Spirit Battle rematch would notify players for event bonuses, but does not actually offer any bonuses.