-An attack's power decreases on a curve after each successive use, first dropping sharply, then slowly bottoming out to a bit less than half the attack's max power after about 8 uses. You recharge your moves by using different attacks. It doesn't matter if you spam 1 attack, it will still recharge your other previously used attacks.
-Attacks that are bottomed out will recharge faster than attacks near max power. For example, if you use attack A for the first time, then a different attack, then A again, the second A will be weaker. However, if you weaken attack A to its minimum power, then use a different attack, then A again, the second A will be a bit stronger.
-The game remembers a lot of your attacks. I'm not sure if there's a threshold for the number of other moves you need to do before it forgets about a worn out attack and resets it (I know it remembers at least 12). I mean, I did 23% with Ike's Fsmash, did 8 other attacks, and my next Fsmash did 21%. It seems a max power attack will maintain its power with about 10 other attacks between each use, though.
-When you die, your power levels get reset. Zelda/PT can also reset their power through switching(!). Your power levels are not increased by waiting, attacking thin air, attacking someone who is blocking, getting attacked yourself, or switching your attacks to someone else (thus, attacking marth then sheik then marth with one attack will weaken it just as much as using it on marth 3 times).
-All attacks refresh other attacks equally. If you weaken attack X through repeated use, 10 weak jabs will recharge it just as much as 10 fully charged smashes. Different hits of A combos count as seperate attacks, as do seperate throws and throw punches(!). However, repeated hits of infinite punches (like sheik, fox, etc) and drill attacks (mario's Dair) do not count as seperate. Projectiles are weird, too: only the first needle in Sheik's needle storm counts.
-Attacking someone who's countering doesn't count. It counts for the counterer, though, so each successive counter will be weaker, regardless of the attack they're countering.
-Attacking an object DOES count. For example, attacking wario's bike, any destructible things like the walls in MGS land or Luigi's mansion, etc.
-There's a tiny bit of randomization in the damages
- damage doesn't decrease in training mode. This confused me for a while.
