The 1v1 multiplier is a mechanic in Super Smash Bros. Ultimate designed to speed up matches between two players. In short, when a game has only two players, and items are off, characters take 1.2x damage from all sources.
The 1v1 multiplier is a damage-taken modifier rather than a damage-given one, and is applied after all other calculations. As a result, it does a few unintuitive things:
- It does not affect the amount of damage needed to KO an opponent. If a move will KO at 120%, it will do so whether the 1v1 multiplier is on or off.
- However, it does mean that the opponent will be at higher damage before the last hit of a multi-hit move connects, and thus the move will effectively KO earlier.
- It does not affect the length of hitstun, freeze frames, shieldstun, status effects such as bury or sleep, and so on.
- It does not cause projectiles to break through reflection earlier.
- It amplifies recoil damage and hoop damage, but it does not alter healing.
- It is active in training mode when there is only one CPU opponent. Adding more CPUs disables it.
Shields and stage elements are unaffected by the multiplier, though most other player-created objects are (such as Pikmin or K. Rool's belly).