The Gangreen Gang is at an underground subway, where all of the Gang soon get up after seeing an oncoming train, except for Big Billy. Due to his weight, he is unable to get up. Suddenly, thePowerpuffGirls come and rescue Billy from sudden death. The next day, Professor Utonium announces that the Girls have a visitor---Big Billy, who has switched sides following the incident. Suddenly, the phone rings, and the Mayor has a call stating a bank robbery is in place. Thanks to Big Billy's weight, the robbers get away. The phone rings again, this time to explain an art theft at the Townsville Museum. Big Billy destroys valuable and irreplaceable art to avoid the thief from escaping. However, at the third call, a giant monster is attacking Townsville. However, when Big Billy tries to destroy the monster, he ends up destroying Townsville. Blossom gets angry. Bubbles and Buttercup sees her and asked her if she is ok. Blossom furiously flies to, scolds, and yells at Big Billy for letting the bank robbers getting away, destroying irreplaceable art, and now destroying all of Townsville, demands that he "caused much less collateral damage as a member of the Gangreen Gang", and orders him to leave. Saddened by the message, Big Billy obeys her order and returns to the Gangreen Gang, where they stage a plot to get revenge. The Gang are back at the underground station, where they try to trick the Powerpuff Girls into going down there. Suddenly, Big Billy traps all of them in a steel bar, but comes later and rescues them upon hearing the word "choo-choo". However, the Powerpuff Girls then give each Gangreen Gang member a beating, indicating that "crime doesn't pay".
Running gag: Billy willing to help the Girls and saying "Billy help".
Buttercup still hates broccoli, maybe she hasn't gotten over eating it so much in "Beat Your Greens".
When Billy finishes off his story on how the girls asked him to leave, he finished with "I came back here." He mostly speaks in the third person.
The line that Ace says when Big Billy is about to save the girls 'Don't be a hero, Billy' is a reference to a popular anti-war song by Paper Lace. "Billy, don't be a hero" is also said in the Justice Friends segment "Valhallen's Room" on Dexter's Laboratory.
Season 1:Monkey See, Doggie Do • Mommy Fearest • Insect Inside • Powerpuff Bluff • Octi Evil • Geshundfight • Buttercrush • Fuzzy Logic • Boogie Frights • Abracadaver • Telephonies • Tough Love • Major Competition • Mr. Mojo's Rising • Paste Makes Waste • Ice Sore • Bubblevicious • The Bare Facts • Cat Man Do • Impeach Fuzz • Just Another Manic Mojo • Mime for a Change • The Rowdyruff Boys • Uh Oh Dynamo Season 2:Stuck Up, Up and Away • Schoolhouse Rocked • Collect Her • Supper Villain • Birthday Bash • Too Pooped to Puff • Beat Your Greens • Down n' Dirty • Dream Scheme • You Snooze You Lose • Slave the Day • Los Dos Mojos • A Very Special Blossom • Daylight Savings • Mo Job • Pet Feud • Imaginary Fiend • Cootie Gras • The Powerpuff Girls Best Rainy Day Adventure Ever • Just Desserts • Twisted Sister • Cover Up • Speed Demon • Mojo Jonesin • Something's a Ms. • Slumbering with the Enemy Season 3:Fallen Arches • The Mane Event • Town and Out • Child Fearing • Criss Cross Crisis • Bubblevision • Bought and Scold • Gettin' Twiggy With It • Cop Out • Three Girls and a Monster • Monkey See, Doggy Two • Jewel of the Aisle • Super Zeroes • Candy Is Dandy • Catastrophe • Hot Air Buffoon • Ploys R' Us • The Headsucker's Moxy • Equal Fights • Powerprof. • Moral Decay • Meet the Beat Alls • Helter Shelter • Power Lunch Season 4:Film Flam • All Chalked Up • Get Back Jojo • Him Diddle Riddle • Super Friends • Members Only • Nano of the North • Stray Bullet • Forced Kin • Knock It Off Season 5:Keen on Keane • Not So Awesome Blossom • Power-Noia • Monstra-City • Shut the Pup Up • Toast of the Town • Divide and Conquer • Burglar Alarmed • Shotgun Wedding • Save Mojo • Substitute Creature • The Boys Are Back in Town • See Me, Feel Me, Gnomey • Pee Pee G's • Boy Toys • Seed No Evil • The City of Clipsville • Lying Around the House • Bubble Boy • A Documentary • Girls Gone Mild • Curses • Bang for Your Buck • Silent Treatment • Sweet 'n' Sour Season 6:Prime Mates • Coupe D'Etat • Makes Zen to Me • Say Uncle • Reeking Havoc • Live & Let Dynamo • Mo' Linguish • Oops, I Did It Again • A Made Up Story • Little Miss Interprets • Night Mayor • Custody Battle • The City of Nutsville • Aspirations • That's Not My Baby • Simian Says • Sun Scream • The City of Frownsville • West in Pieces • Crazy Mixed Up Puffs • Mizzen in Action • Roughing It Up • What's the Big Idea? • Nuthin' Special • Neighbor Hood • I See a Funny Cartoon in Your Future • Octi-Gone Reboot:
