"Arms Race with Legs" is the thirty-first episode of Season 3 of Teen Titans Go! and the one hundred and thirty-fifth episode overall. It first aired on 5 May 2016 on Cartoon Network.
When her teammates turn evil, it's up to Lady Legasus to stop the League of Legs.
While the rest of the Teen Titans gather at the couch, Beast Boy stretches in front of them and explains to Raven that he plans to jump and touch the door jam to show how cool he is. Raven disagrees with him, but after he jumps, he impresses Cyborg, Starfire and Robin. They each take turns jumping and touching the door jam and Raven tells them to stop as it isn't cool. Beast Boy refuses and he, Cyborg, Starfire and Robin spend the rest of the day jumping and touching objects. Back at the living room, Robin challenges them to jump and touch the ceiling light. Starfire, Beast Boy, and Cyborg tell him he won't be able to, but Robin jumps and touches the light. Cyborg demands an explanation and Robin claims it's because of his tight butt. Raven appears and tells them that jumping is because of legs, but Robin laughs and challenges he to prove it. Raven declines, claiming that the power of legs isn't to be used for fun and games. The other Titans begin making fun of her and Raven transforms into Lady Legasus in order to hit the ceiling fan higher than Robin.
Starfire says that they wish to leg jump like Lady Legasus but she refuses, claiming that leg power can be intoxicating and lead to bad things if unchecked. After Beast Boy flatters her legs and the Titans encourage her to change her mind, Lady Legasus agrees to a little fun. Cyborg transforms into Thunder Thighs, Starfire becomes the Incredible Quad, Beast Boy turns into the Calf, and Robin changes into Captain Cankle, reforming the League of Legs. The League of Legs jump around Jump City, touching various objects and Batman. At night, the League of Legs overlook Jump City on a cliff and Lady Legasus tells the League that their legs have to be put away.
The next day, Raven notices that the Titans haven't abandoned their League of Legs personas and are using their legs for menial tasks. The Incredible Quad says they attempted to put the legs away, but the legs refused. Raven claims that because they're using their legs improperly, their legs are taking control of them. Captain Cankle, Thunder Thighs and the Incredible Quad claim that they're following Raven's example as she used her legs improperly to prove Robin wrong and enjoyed jumping around town with them. Raven is unable to make an excuse, but begs them to stop. The Calf challenges her to and the four jump through the roof and onto the ceiling. Raven follows and sees them hitting an eagle, breaking a rainbow, slapping a cloud, and knocking down an airplane. She transforms into Lady Legasus and uses her legs to save the plane.
Lady Legasus orders the League of Legs to disband, but Captain Cankle challenges her to a contest between them. If Lady Legasus wins, they'll disband, but if Captain Cankle wins, she must leave the League. Lady Legasus refuses, but they begin making fun of her. She accepts and Captain Cankle wishes her luck as he has a leg up the competition. He shoots into space and slap an astronaut's butt, but when Lady Legasus tries, she fails. Lady Legasus is shocked that her legs failed her and warns the League that their legs are becoming evil. Captain Cankle reminds her of their deal and she reluctantly becomes Raven again. The League resume jumping and touching in Jump City, but start breaking everything they touch.
Raven observes from Titans Tower and throws her leotard in frustration when weights roll out. She realizes that the League rigged the challenge and transforms into Lady Legasus. She confronts the League of Legs in front of the ruins of Jump City Museum, but she is easily defeated. Captain Cankle tells her to join them or face the consequences, but Lady Legasus calls upon the ancient spirit of legs and transforms into Mega Legasus. The League of Legs lock legs and attack with Leg Lock, but Mega Legasus breaks their formation and attacks the members individually, breaking their legs. Robin, Cyborg, Starfire, and Beast Boy apologize for their mistreatment of legs and thank Mega Legasus for stopping them. Robin says he'll never use his legs again, but Mega Legasus reassures that he'll earn the right to become Captain Cankle again. Robin clarifies that he won't be able to use his legs again, because they're broken badly.
For a full transcript of "Arms Race with Legs", click here.
Raven transforms into Lady Legasus again, having previously done so in "Legs" and "Leg Day". Cyborg, Starfire, Beast Boy and Robin also transform into Thunder Thighs, The Incredible Quad, The Calf and Captain Cankle and form the League of Legs again.
Robin says "Sorry" when jumping and touching Batman, referring to his fear of him as revealed in "Sidekick".
Starfire and Cyborg warn Robin not to be an Icarus, referencing a figure in Greek mythology who was overconfident when flying with man-made wings and fell to his death.
Cyborg, Starfire, Beast Boy and Robin reference Sailor Moon when they transform into Thunder Thighs, The Calf, and Captain Cankle.
When Beast Boy jumps onto Lady Legasus' legs, another Beast Boy can be seen by Cyborg and Starfire.
The Image Gallery for Arms Race with Legs may be viewed here.