Stale-move negation

Stale-move negation, also known as staling or move decay, is a gameplay element in Super Smash Flash 2 that affects the damage of a character's attacks. Whenever a player lands the same move multiple times in a row, the move becomes "stale", with its damage decreasing as a result. The more frequently or recently a certain move hits within a certain frame of reference, the weaker it will be. Moves not yet affected by stale-move negation are referred to as fresh and deal additional damage. This is used to discourage players from repeatedly using the same moves and incentivize them to utilize the character's whole moveset.

The staleness of a move applies to the move as a whole, rather than particular hits or hitboxes. Thus, a move with multiple hits will only be affected up to one time when used, and each hitbox of a move suffers from the same staleness. Similarly, all charge levels of a chargeable move share the same staleness. However, the grounded and aerial variants of special moves are counted separately.

Most projectiles and items are not affected by stale-move negation, instead always being considered fresh. The same applies to pummels, taunts, and Final Smashes.

Stale-move negation is not present in Training, which keeps the damage values of attacks consistent without applying multipliers based on usage.

Calculation
To calculate the staleness of any move, a queue is used. Whenever the player lands a move on an opponent, it is then considered stale and pushed to the front of the queue. Up to nine moves can be stored in the queue during a match, and each new move added to the queue pushes each of the following moves into the next position of the queue. When a move is repeated in the queue, its damage is decreased through a multiplier based on both how often the move appears in the queue and how recently the move has been used in each position.

Each position in the queue has a "reduction factor", with later positions having smaller reduction factors. The sum of the reduction factors for each position a stale move is stored in is then subtracted from 1 to calculate the damage multiplier to be applied the next time the move is used. For instance, positions 1, 2, and 6 of the queue have reduction factors of 0.1, 0.09, and 0.05, respectively, which have a sum of 0.24 when added together. Therefore, a stale move in these positions will deal 24% less damage, or 76% of the damage it would normally deal.

If a move is not on the queue, then it is considered fresh and has a damage multiplier of 1.05. As a result, attacks effectively never deal exactly their base damage, as they will either be fresh and deal bonus damage or be stale and deal less damage.

The following table lists the reduction factors for each position in the queue.