Attack Power Decay
This game "punishes" the repeated use of the same attack by decreasing BOTH the DAMAGE and KNOCKBACK a move does.
Attack Queue
The game keeps track of this by having an "Attack Queue" where it remembers the last 9 attacks that you landed on your opponent. If your attacks are getting weaker than you would like, just hit with several other attacks, and then your other moves will soon be back to full strength.
Decay Amount
A multiplier is applied to both the launch speed and damage dealt by an attack that depends on where in the attack queue that move already appears.
The following image (by ColinJF) shows how the different positions in the attack queue affect the decay multiplier.
The leftmost spot indicates the most recent attack in the queue and the rightmost spot indicates the least recent attack in the queue.
To find the decay multiplier, simply add up all of the values indicated for the given attack spot and subtract that from 1.
I thought we could do move impressions like this thread
http://www.smashboards.com/showthread.php?t=165745