PIS is term familiar to fans of Western superhero comics which means 'Plot Induced Stupidity'. It's where an author deliberately ignores or under-utilises a character's abilities to make him/her lose a fight. In Naruto I've seen fairly high amounts of it, especially in Part II, and especially to nerf its supposed main character.
1.After 2.5 years of training unders Sainins Sasuke learns some dozen odd new jutsus, Sakura learns all of Tsunade's techniques except slug summon and Naruto learns...Odama Rasengan(and later, a basic genjutsu counter).
2.The same boy who learnt Rasengan(a technique that took Yondaime 3 years to create) in a week can only complete the Rasenshuriken to 50% after 20 years worth of training(even Naruto can't be that dense!).
3.After finally learning a new technique he can't use it because it damages his arm. Here Kishimoto totally ignores the obvious solution of letting a Kagebunshin deliver the Rasenshuriken.
4.Kagebunshins have the same chakra as the real Naruto and can do the same jutsus but die with one punch. Hence if he swarms an enemy with KBs the enemy always beats him.
There are others, and for other characters as well. Do you guys have any more to add, or discuss the above?