Originally Posted by IXI ANIMO IXI
another point to make is that there are numerous jounin that haven't mastered 2 elements/nor shown the ability to even use one....kurenai,shika's,gai,neji,zabuza.. ....sure there are plenty more
For starters, it was flat out stated in the manga that Jounin are supposed to know how to use at least 2 elements
. I linked that already.
Second, for your list, you use specialists that utilize unique abilities at high levels of skill, or have a kekkei genkai.
-Kurenai: genjutsu specialist said to be on a level with Itachi, and praised by Itachi for her skill. Hasn't shown using anything but genjutsu, but has not been said to only know genjutsu (saying she doesn't use anything else is arguing from ignorance).
-Shika's: I'm assuming you mean Shikaku, Shikamaru's dad. He's the leader of the Nara clan, and extremely proficient at the shadow binding technique (which is taught only to members of the Nara clan). Another specialist that has not been said to not know how to use other elements besides Yin. If you mean Shikamaru in that, you are sorely mistakened. Shikamaru is still a chuunin. Aside from Neji, the only other members of that particular chuunin exam that made it past Chuunin were Temari and Gaara.
-Gai: As has already been mentioned, he knows how to use ninjutsu. He's been shown using an advanced space/time ninjutsu, summoning. He's a jounin, so he has to know at least 2 elements. He specializes specifically in taijutsu because of his natural talent for the 8 Gates.
-Neji: A genius with a kekkei genkai. Neji, as a genin (maybe before), was able to master techniques that were hidden from him because of his house status, all on his own.
-Zabuza: Not from Konoha, nor was he ever stated to be a Jounin. Even if he was Jounin, how the Mist selects Jounin (or any village) is unknown. They may not have the same 2 element requirement that Konoha does. He was from the Mist's version of ANBU, which takes no bearing for age/gender/background/previous rank. His skills were what brought him to the ANBU, since he was able to kill 100 students of a graduating class before he even entered the academy and was part of the most dangerous generation of Mist Swordsmen.
The abridged version: it has been declared that Jounin of Konoha are required to know at least 2 elements. Just because a Jounin hasn't been shown to use those elements, or a class of jutsu, doesn't mean they don't know it. Unless it is otherwise stated, what Kakashi said goes.