Originally posted by: Mut@t@
Stop trying to spread misinformation. It specifically said in the manga, that sharingan can copy, read, and defeat all jutsus except bloodline jutsus.
Unless they go beyond the capabilities of the sharingan user. Copying a summon is no good if you haven't subscribed to the creatures service. The copy will fail or be useless.
Copying some taijutsu is no good if you can't keep the speed. The copy will fail or be useless.
Copying some weird-ass large ninjutsu is no good if you don't have enough chakra. The copy will fail or be useless.

The only thing we've seen from Jiraiya that can be instantaniously copied is his hair-armor and the swamp iirc. Everything else required some sort of training even if you figured out how it works, or a summon-contract. Well, Rasengan could be instant-copy too, depending on your chakra control level.