Some of the basic ninjas like you already stated have skillbooks in other servers such China and Germany. There's a list of skillbooks/skillbreaks floating on the forums, just search for it in the search bar.

It's up to Oasis when they want to release more skillbooks. I'm waiting for the gaara's as his is good.

Wow, a Fragment's Note avatar? And you even chose Tsukasa O.O

Actually though, I'm pretty sure most of the ninjas you mentioned already have Skillbooks. You'll just hafta wait till they come out.

I dont even remember their skills just wait as always haha

SB ninjas are a must for Gimpfelkampf event (don't know the name in english), since older characters cost less points and could still be used with proper breakthrough.

Hmm, interesting