In an attempt to encourage players to use a variety of attacks, moves get weakened immediately after use. As you play, the game scales damage and knockback (with the exception of throws) for attacks by keeping track of the most recent four that were used per player.
| Staleness Level | Attack |
|---|---|
| Stale 1 (maximum): Multiply damage by 0.75 and round up1 | (most recent attack goes here) |
| Stale 2: Multiply damage by 0.82 and round up | (second most recent attack) |
| Stale 3: Multiply damage by 0.89 and round up | (third most recent attack) |
| Stale 4: Multiply damage by 0.96 and round up | (fourth most recent attack) |
The game has a copy of this table for each player, and it describes how the attack’s damage and knockback will change the next time it is used.
When an attack does damage2, it goes into the top right box of that table, pushing any other moves down. If the attack is already in the table, it gets moved back up to the top. If an attack is in the “stale 4” slot and gets shifted down, it is removed from the table and is no longer stale.
Note that because damage is dealt in integers with damage scaling for stale moves rounding up, this means that any move doing less than 25% damage when fresh will do the same damage at stale 4:
Since this describes almost all moves in the game, you can just remember this as a rule of thumb:
After you hit someone with an attack, that attack is now maximum stale. Attack with three different moves to un-stale the first attack.
Practical example
You’re Pikachu and you hit Yoshi off the stage with the combo:
- Back air
- Down air
- Back air
- Forward throw
If Yoshi is at 85% will back air break super armor? Use Yoshi Armor Break Percentages
Expand for solution
By the end of the combo, back air will be in the “stale 2” slot in the staleness table above. According to Yoshi Armor Break Percentages, Pikachu’s stale 2 back air will break super armor if Yoshi is at least 89%. Because in our example Yoshi is only at 85% it will not break super armor.
Projectiles
Link’s boomerang gets stale, but not his bomb. How does projectile staling work?
This is complicated and a little contrived. To answer this we have to break projectiles into two categories: weapons and items.
Weapons: Fox’s laser, the RayGun item’s laser, fireballs, thunder jolt, fire flower, the PK fire projectile, Link’s boomerang. These attacks that come from a player or are granted by an item do stale.
Items: RayGun, Fan, Link’s Bomb, shells, the pillar of fire that appears when PK fire connects. Damage done by an item not currently being held (including collision) does not stale.
Random facts
- Throws do stale, but knockback is not affected.
- Forward and back throws count as different moves.
- Dying does not reset the player’s stale moves.
- Angled moves (e.g. Falcon’s high angled forward smash) do not count as different moves for staleness purposes.
- The Hammer item’s attack does not stale.
Acknowledgements
Thanks to VtR in the Smash 64 discord for answering my many questions about item/projectile staleness.
Footnotes
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These scaling constants came from the Smash Wiki article Stale-move negation ↩
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Update: Technically this is wrong but it’s close enough. Jigglypuff’s up b doesn’t do damage but it still counts for staleness purposes. ↩