One Tail: seen in the first battle with Sasuke at the Valley of the End.
Two Tails: seen during the Rescue of Gaara Arc, seriously injuring Deidara.
Three Tails: seen in the cultivation with Jiraiya, seriously injuring Jiraiya.
Four Tails: seen in the battle with Orochimaru at Tenchi Bridge.
Six Tails: seen in the fight with Pain, covered with bones of the Nine-Tails.
Eight Tails: seen in the fight with Pain, after being sealed by the Catastrophic Planetary Devastation, the Nine-Tails flesh and blood could be seen.
Nine Tails: seen during the Fourth Great Ninja War.