In What Episode Does Naruto Fight Pain?
The fight between Naruto and Pain takes place over seven episodes, from 163 to 169. The majority of the fight between Naruto and Pain takes place in "Planetary Devastation," episode 166, which is episode 14 of season seven.
In season seven, episode 10, "Explosion! Sage Mode," Naruto begins the fight by taking on the paths of Pain. The fight continues through four episodes in season seven: Episode 11 "Danger! Sage Mode Limit Reached," Episode 12 "Nine-Tails, Captured!" Episode 13 "Confessions," and, Episode 15 "The Fourth Hokage. The end of the battle takes place in episode 169, which is episode 16 of season seven, titled "The Two Students."
The episodes originally aired in Japan from June 3 through July 22, 2010.