The Nu Stone is my own creation. In Chrono Trigger, there are these big blue guys named Nu. You learn how to tickle and scratch one in Queen Zeal's palace. Well, try scratching the back of the Nus you fight in 65,000,000 B.C. In FB, if you can do so (very difficult; Nus are REALLY hard), you get the Nu Stone.
What the Nu Stone offers is this: a Nu Tech Attack, where people turn into Nus and batter the enemy in their own way. One is always holding his hands up and looking to the sky, one person is always ready to attack, and one person is always attacking. The three jobs are cycled all the time.