Teen Titans switches Starfire and Raven. The voices switch in this version too, but the reason is apparently not due to appeasing children; Hynden Walch and Tara Strong were apparently able to duplicate one another's voices for their respective characters so well, the producers thought it would be pointless to continue having them voice one another's characters.
Also implements How Do I Shot Web?; Starfire has to bare her emotions to the world in order to use her powers, while Raven has to suppress her emotions just to keep her powers under control. Hilarity Ensues as they struggle to adjust.
Kim Possible and her sidekick Ron are the subject of this evil-experiment-gone-wrong (though for the villain it did in fact work, allowing him to get control of the Wave Motion Gun) in one of their funnier episodes. The prospect of a teenage boy being stuck in a girl's body is explored as far as Disney would allow: only a throwaway comment about Ron liking a skirt. (Also, "Your hair is so...flippy!"). It also featured Anne Possible, as a brain surgeon, complaining that mind swapping is totally impossible.
Played for laughs at the end of "Dragon Breath"; when the soul-stealing nix returns everyone's souls to their bodies, Trixie and Spud get switched. The final scene of the episode is them sitting in the now-deserted dance hall, trying to figure out what happened, which leads to this hilarious exchange:
Trixie *in Spud's body*: Sweet mama flapjacks, please tell me I'm lookin' at a mirror!
Spud *in Trixie's body*: Dude, I could have sworn I was a dude!
A multiple body swap is the plotline of The Powerpuff Girls episode "Criss Cross Crisis": Buttercup switches with the Professor (and freaks out about finally having fingers), Blossom switches with Sara Bellum (and accentuates her newfound curves), and Bubbles switches with the Mayor (and rationally accesses the whole situation after a beat), and then some. There's one shot showing a theater showing Freakin' Friday, just to imply where they got the idea from.
This is a particularly interesting example, in that a hero and villain switch brains, which lends itself to certain tactical advantages and makes it all the more important to "set things right". Luthor attempts to use this opportunity to discover Flash's secret identity, but he is thwarted upon looking in the mirror and realizing that he has "no idea who this is".
Another reason for this episode's notable status regarding the trope is that this is a rare example of the filmmakers going out of their way to accurately portray the switch in the characters' behaviors. In this case, what stands out is that Michael Rosenbaum (Flash) and Clancy Brown (Lex Luthor) recorded their parts together. Each actor providing the line readings for their original characters, and the opposite actor would mimic the line reading. This allowed Clancy Brown's Luthor to have the exact timing and delivery of Rosenbaum's Flash, and vice versa.
Clancy Brown's show-stealing performance as Flash-in-Lex also led to some of the funniest moments in the series.
Dr Polaris: Aren't you going to wash your hands? Flash-in-Lex:No. 'Cause I'm evil.
Flash-in-Lex: My fellow bad guys, I, Lex Luthor, your leader, will speak now about my, Lex Luthor's, plan. My villainous, villainous plan. Question the plan at your peril! Uh... any questions?
Plus, Lex-in-Flash is so dangerous that it's scary. Trapped in the Watchtower and hunted by the entire Justice League, Lex-in-Flash is nearly unstoppable, figuring out how to use all of the powers that The Flash intentionally doesn't use, due to how dangerous they are (namely explosive phasing and minimally controllable Not Quite Flight).
Tale Spin has an example of the adult/child switch in the episode "A Baloo Switcheroo", with Baloo and Kit getting zapped by an ancient totem; later in the episode, Rebecca and Don Karnage do the protagonist/antagonist switch.
Then after they switch back at the end of the episode, two of Don Karnage's lackeys have ended up switching.
Darkwing Duck has a double adult/child switch, swapping Darkwing with Gosalyn and Launchpad with Honker. In addition to trading voices, the switched characters also trade eye shape and color.
This one does deal with the voice issue; at one point to help fool J. Gander Hooter (Darkwing's occasional Da Chief), Darkwing (in Gosalyn's body) sits in Gosalyn's lap (from Darkwing's body) and uses his voice to talk to him. Earlier, they pass it off as Darkwing imitating a little girl's voice.
An episode of the original Teenage Mutant Ninja Turtles has Splinter and the Shredder swapping brains. It features Splinter-in-Shredder's-body fooling Krang's brain-scanning machine by thinking, "I am Shredder. I am Shredder."
It at least averts Voices Are Mental, which is rare for a cartoon show. Their respective voice actors stayed the same. (James Avery for Shredder and Peter Reneday for Splinter) did a pretty good job switching roles.
Don't forget the episode where Raphael switches with a taxi driver.
Code Lyoko episode 42, "A Fine Mess", has Odd switching bodies with Yumi. While Yumi plays things fairly straight for the one day and night they are afflicted, Odd is challenged by his lack of knowledge of Japanese customs and language while living with Yumi's family. He further aggravates Yumi by digging through her closet, complaining about wearing a bra (yes, he actually does this, though the word "bra" is avoided), and showing up at school in a Cat Girl cosplay outfit; most fitting, as the virtual, Lyoko version of Odd has distinctly Cat Boy features.
In one Adventures of the Gummi Bears episode, Big Bad Duke Igthorn swaps bodies with Tummi to gain access to the Gummiberry Juice. Fortunately, Igthorn's scheme fails when he discovers that the juice affects humans and Gummi Bears differently.
In the Captain Simian And The Space Monkeys episode "Escape from the Plant of the Apes", Captain Simian and Shao Lin switch bodies. Hilarity Ensues — but it's well thought out hilarity. Voices Are Mental is averted; not only do Simian and Shao Lin's voices stay in their original bodies, but their voice actors (Jerry Doyle and Karen Maruyama) use each others' speech cadences while their characters are switched. As noted above, these details are usually overlooked in Freaky Friday Flip stories.
In the Centurions episode "Double Agent", Doc Terror switches Ace and Hacker's minds as part of an evil plot.
This happens to Lily and Mitsuki, the two heroines of the Nicktoon Kappa Mikey who are also roommates, through a pair of friendship bracelets, in the episode "Manic Monday".
An episode of The Tick features a particularly outrageous example, with more than half a dozen characters randomly swapped. Including a zebra and a creature made entirely of tongues.
Arthur:(in disgust and horror) I can taste the floor... I can taste everything!
In the episode "The Unbearable Blightness of Being" from Captain Planet And The Planeteers, Dr. Blight switches bodies with Gaia. Blight!Gaia starts wrecking the environment For the Evulz and Gaia!Blight uses her gadgets to reverse the damage. After getting back her body with help from the Planeteers and Capt. Planet, Gaia tells the Planeteers that the experience taught her that technology can be put to good use.
This is possibly one of the most Fridge Logic heavy examples of this trope: how do you switch bodies with the spirit of the Earth?
Do not even try to come up with some sort of internal consistency on that show about how spirits work, including whether or not Gaia floats around Hope Island like a sparkly ghost or walks around like a flesh-and-blood human.
In Ben 10 Gwen and her nemesis Charmcaster switch bodies first, then Charmcaster is restored to her rightful body only to have Gwen and Ben switch bodies. Everything is set right in the end, naturally. Interesting in that voices-go-with-bodies in the Gwen/Charm switch, but voices-go-with-minds in the Ben/Gwen switch. And Charm-as-Gwen manages to fool Ben and Grandpa, despite having no opportunity ever to observe their normal interactions.
In The Secret Saturdays a benevolent professor makes the swap himself with a Hibagon (giant, gorilla-like monster), only to have the method of swapping back destroyed in the resulting hubbub. That fate of the Professor's body is not touched upon.
Ruby-Spears Mega Man, "Bot Transfer": Mega Man unwillingly switches bodies with Snake Man, of all robots. His reaction is quite logical. (Notably, their voices stay with their bodies.)
Kind of done in Transformers Animated. As revenge for having him arrested as a spy and turning him into a fugitive, Wasp disguises Bumblebee as himself and vice versa. This involves switching their helmets and vocalizers along with their paint jobs, and since they share the same basic bodymold it's as good as a body swap.
Lilo And Stitch The Series has this happen to Lilo with Stitch, Gantu with Hamsterviel, and Jumba with Pleakly for most of the episode. Toward the end, the heroes are re-swapped in a four-way switch. Everyone kept their original voice, but it probably would have been a little odd to hear Lilo's/Jumba's words in Stitch's voice anyway (Stitch is just a step away from The Unintelligible.)
An episode of Garfield and Friends does it when Garfield and Odie touch a mysterious idol together. At the end of the episode, the idol gets broken, Jon and the gypsy owner of the idol pick up the pieces... and also get swapped. In both cases, it goes unnoticed (only Garfield notices at a certain point that he became a dog).
Here Voices Are Mental is justified at least with Garfield. What we hear is actually Garfield's thoughts, not his voice, so it makes sense that Garfield in Odie would sound the same. No excuse for the others, though.
An episode of The Garfield Show also has Garfield and Odie swapping their bodies, though an alien is behind it in this case.
Phineas And Ferb has "Does This Duckbill Make Me Look Fat?", where Candace and Perry switch bodies because of the title boys' newest invention, and Perry goes off to stop Doofenshmirtz like always... but in Candace's body ("Perry the Teenage Girl?!"). The end credits even included a Candace-ified version of Perry's theme song.
In one episode of Sushi Pack, Wasabi and the Mayor swap brains, thanks to some sea-unicorn dust. At first both are ecstatic, since the Mayor gets to be a hero like he always wanted, and Wasabi gets to actually go through with the Mayor's campaign promises, but both soon learn that being each other is harder than they thought.
Agent K and Dick accidentally swap bodies in an episode of The Replacements. A rare case where the voice-actors imitate each other.
Parodied wonderfully on American Dad. Stan and Roger get into an argument over whose life is easier, and end up both saying "I wish we could trade places!" while touching an Incan bowl that supposedly grants wishes. At that moment, the lights began flashing and a strange moan is heard...it turns out to be Klaus, playing with the light switch and making funny noises. Nothing magical happens, but the two decide to trade lives anyway.
Klaus later says that "if that had been a real wish-granting bowl, it would be in the back seat of a Ferrari driven by a 600-year-old Incan on his way to his job as Jessica Alba's G-string."
In an episode of Jimmy Two Shoes, Heloise does this to Beezy and Cerbee after they ruin her private picnic with Jimmy. At the end of the episode, Jimmy and Heloise have switched bodies, which she refuses to fix until they have that picnic.
One episode of The Secret Show has the two main characters, Victor and Anita, switch minds due to an unusual mix-up with...um, 'brain chunks'.
A British animated series called Bounty Hamster has an entire episode full of body-swaps. A criminal steals a body-swapping device and uses it to go joy riding in other people's bodies. Highlights of the ep are a human, teenage girl stuck in the body of a humanoid rhino, a body-swap conga line with over half a dozen body-swaps in a row and the criminal, teenage girl and a hamster, bounty hunter all being stuck together in the same body, where they try to beat each other up. The insanity ends with the criminal's mind trapped inside of a cactus.
Happens in the Potatoes And Dragons episode "It Wasn't Me", between King Hugo and the Dragon. Interestingly, whilst the Dragon is in King Hugo, the Dragon retains his ability to breathe fire, leading to King Hugo running around spouting flames.
In one of the new episodes of Futurama the Professor perfects a mind-switching machine, only to discover that the "brain immune response" making it impossible for a given pair of bodies to swap more than once. Soon the entire cast is switching bodies for various reasons (reliving one's youth, showing up one's girlfriend, stealing the crown of the Robo-Hungarian emperor, etc.), and confusing Hilarity Ensues.
The voices switch, even though it's an adult program. A reviewer implicitly thought the swapping in the episode was confusing to adults as well.
One of the writers proved a mathematical theorem stating that bodies can be returned to their original owners with at most two extra people. The theorem is explained in the episode, and it is possibly the geekiest case of Shown Their Work ever.
The trope is also played with in an earlier episode where Fry's head is attached to Amy's body and the one where Nixon's head-in-a-jar acquires Bender's.
Pepper Ann switched places with her mother, Lydia, during a meteor shower. The Trope Namer was alluded to when Lydia discovered that Pepper Ann still hadn't returned a VHS labeled Trippy Tuesday to the store.
In the Action League Now episode "Hey! Who Stole My Face!" the League follows The Mayor's orders and The Chief is put in jail. However, the two didn't really switch bodies; an operation after a blender mishap simply results with one having the other's face.
Happens in an episode of The Pirates of Dark Water, where the main hero and villain switch places so that the villain could steal all the treasures. To make things slightly more interesting their reflections also switch and they don't switch voices.
This occurs in the Danny Phantom episode "Splitting Images", when Poindexter takes over Danny's body to show the latter what it feels like to be bullied.
An episode of Yogis Treasure Hunt involves a machine used by Dick Dastardly to accomplish this. As a result, Yogi switches with Boo Boo, both Augie Doggie and Doggie Daddy, and Snooper and Blabber switch with each other, along with Snagglepuss and Ranger Smith, and Quick-Draw McGraw and Huckleberry Hound. Eventually, Dick Dastardly and Muttley end up switching places as well.
And then at the end, Muttley swaps with FREAKIN GODZILLA!
Fantastic Four had a variant on the standard Freaky Friday Flip trope. Rather than switching bodies, the Four ended up switching powers.
The original Thunder Cats epsiode "The Shifter" had body-swapping related shenanigans, and the voices are switched in this version too. First Snarf and Panthro get switched, then Slithe and Jackalman, and then Lion-O and Wilykat! The best part? Vultureman (its creator) didn't even build the thing with a "reverse" option! Extra fun: The Sword of Omens requires both the right bloodline and the right mind/spirit/heart to be activated. Neither Kat-as-Lion-O or Lion-O-as-Kat can use it. Monkeyine and Slithe also get switched near the end.
Robotboy does this first with Robotboy and Gus when the latter gets electrocuted reaching into the former's head during a tune-up, then with Gus and a dove by minor villain Felonious Hexx for revenge on what he did in a previous episode. In the latter case it's actually an improvement because the dove does Gus' schoolwork better and Gus genuinely enjoys life as a dove.
I Am Weasel did this when Baboon and Weasel swapped brains. The doctors at the hospital chose to put the big brain in the big head, and the little brain in the little head — so Baboon's brain wakes up in Weasel's body. "I.R. Weasel!" They also swap voices, but no one else notices that Baboon and Weasel have swapped bodies. Baboon-in-Weasel exploits Weasel's reputation to become mayor, and the city becomes a disaster. Weasel-in-Baboon adopts Baboon's identity, works hard, runs an intelligent campaign, becomes the next mayor and fixes the city. His new slogan is, "I... am... Baboon!"
The 1961 Popeye cartoon "I Yam Wot I Yamnesia" takes a bizarre approach, having characters switch personalities and voices with each other after suffering a bump on the head, and diagnosing it as amnesia.
The Danger Mouse episode "There's A Penfold In My Suit" has the country of Bratyslovakia having been displaced on the map due to a mystic "swapping stone" hidden within an archway in the country. It causes Danger Mouse and Penfold to switch bodies, then Greenback and Stiletto to switch, and then during a chase, everyone gets switched around.
Zig-zag: In the Whats New Scooby Doo episode "A Terrifying Round With A Menacing Metallic Clown," Velma goes off cowering with Scooby after her fear of clowns comes to the surface. Meanwhile, Shaggy—who is determined to win a miniature golf contest—susses out clues with Fred and Daphne. Velma and Shaggy still have their regular voices.
Neds Newt episode "Ned's Newt". It begins with Ned and Newton switching minds due to a lightning strike. Near the end of the episode, while they're attempting to switch their minds back the same way, they end up pulling a security guard and a sandwich into the fracas, all of them switching minds to and fro for a while.
Batman The Brave And The Bold features the epic switch between Batwoman and Batman. Epic because Batwoman does not make the slightest bit of effort to sound or act more masculine as Batman, with Diedrich Bader providing massive amounts of comedy with what seems to be a Camp Gay Batman.