The ninjas are the best at combat and battle and everything that involves with battle(Including the Warriors). They are awesome, and here is a bit about them~
Koi 鯉
The Koi Ninja's can turn into either koi fish or the koi dragon. They can swim really fast, and if they are seen, they will talk to you. They are pretty mysterious, though.
Pansa パンサー
These are the only ninja's that can turn into panthers. They are kind of mysterious, and can be annoying but they are good to fight with and hang around, and a couple of them are seen at the Waterfall Cavern. They love the water.
Ki No Kaze 木の風
These are the wind / tree ninjas, and love to be alone, and only use there powers for the good things in life. They are very strong though, and like to turn into hummingbirds and leaves. These ninjas just like to listen to the wind and things like that. Most of the time they are pretty calm.
Supaiku スパイク
These ninjas are the most snappish. They don't like to be alone, and they tend to mess up. They can be nice, but not usually and they don't like others that much. There constantly at war with the Koi Ninjas, and wish that they could do something with there lives. These ninjas are great barriers, and protection, but they don't like to protect.
Buki 武器
The weapon ninjas only use the finest of weapons, and don't rely on other ninjas to do there dirty work. They like to battle and train, and especially like to tell people what to do and brag. No ninja would dare mess with them, because they would rip you to shreds. They have skills!