I heard they switch bodies by the monster of the week.
Billy as Pink and Kimberly as Blue (MMPR)
In the first season episode "Switching Places," Billy and Kimberly accidentally switch bodies when Squatt messes up Billy's machine. The story didn't match the footage, I would had liked it if they shot some new footage of the Blue Ranger acting like Kimberly and the Pink Ranger acting like Billy. In the reversion, they could had changed the backgrounds but they didn't. Bulk and Skull also switched bodies.
Astronema and Ashley (Power Rangers in Space)
Astronema switches her look thanks to a Body Switcher monster. Astronema as Ashley transformed into Yellow Ranger and Ashleya s Astronema transformed as well.
Sensei, Shane and Dustin (Ninja Storm)
Cam tries to make his father human again, because he is a guinea pig so he accidentally switches bodies with Shane and gets to be the Red Ranger and fight Kelzaks. He then accidentally switches with Dustin and fights Footzilla as the Yellow Ranger.
Yukito and Ryoga of Abaranger
They switch bodies in Episode 27.
Hoji and Wojonian Jinche (Dekaranger) Wojonian ried to escape deletion by switching bodies with Hoji in order to take control of the Deka Base Robo.
Sky and Wootox (SPD)
Wootox had an ability to switch bodies, he pressed his head to Sky and enter his luscious meaty body and even mimic his voice. He took off Sky's translator and he was stuck speaking Wootox's language but it made no sense. If Wootox had a translator, it meant he couldn't speak English so why was he able to speak English in Sky? OR it could be that Sky's body only could speak English and Wootox's body only could speak his language.
Kai and Houka (Magiranger)
Toad changed the brother and sister in Episodes 39 and 40. Houka made reference to having a penis. Anyway, Houka made a better Kai by appealing to the girl of his dreams. Kai complained that he had 'nothing' in his crotch. Anyhoo, they both learn from each other.
In Episode 12, Sosuke changes bodies with a monster. I forgot about this one!
Luka and Don (Gokaiger)
Switched by a monster, Luka used Don's body as a doll and was a better and cooler Don. Don didn't want harm to come to Luka so protected his power. Episode 28.
Shinkenger had a body changing episode but it was with inanimate objects, I wanted to do only human bodies. And yes yes, the monster switched with Chiaki but that was rather quick... The monster went from Chiaki to a ball and Chiaki was in the monster for a while.