Shaman was a word used by Rokugani to describe users of magic in other tribal societies, essentially the equivalents of shugenja.
Nezumi Shaman Edit
Nezumi Shamans, usually called Nameseekers, used name magic and divination. 
Goblin Shaman Edit
Goblin shamans used a corrupted form of elemental magic (kansen).
Zokujin Shaman Edit
Zokujin had shamans too, who specialized in Earth elemental magic. 
Yobanjin Shaman Edit
Although Human, Yobanjin tribes also had shamans. Their magic was also elemental, but more primitive than the one of Rokugan's shugenja.