PIS: Plot induced Stupidly
CIS: Character induced stupidly
PIS: this is when plot decides a winner of a fight between characters in a series but the problem with it is when a character has done enough feats that trumps the other characters feats and the characters with the better feats loses because if he won the plot would have never progressed. Usually with PIS there could have been a better way to advance the plot but the writers chose a way that doesn't make any sense at all.
PIS could occur in tournaments because the writers have to have a certain character win.
Ex of PIS: When Silver was throwing energy blasts back at Enerjak in Sonic Universe Issue 28
This shouldn't be possible considering that Enerjak is nigh Omnipotent and his power should trump Silver's Pschokinesis
CIS: this usually happens when a character could easily win but does something that was not necessary or their personality gets in the way of their victory.
Usually happens to hero characters or characters who show sympathy but the other character takes advantage of it.