- Viewtiful Joe
- Jet Black
- Gadget-Cop - A good cop gone bad when his hero-ness is taken from him. The ammunition from his double 9's must be used against him to be defeated.
- Meta Rangers - These insect-like foes are comprised of Ranger Digi and Ranger Log.
- Killer Hands - The boss of Horror World, Killer Hands has many different weapons at the tips of his hands with which to fight.
- Vanilla - a normally nice person, Vanilla transforms into Alter Woman when her hero-ness is taken from her.
- Queen Heinderella - the leader of the Madow. Queen Heinderella is the one responsible for the theft of the film, and the ultimate boss of the game.
Unlike other games in the series, Viewtiful Joe: Double Trouble! takes place primarily in the game's depiction of the real world instead of its fictional world of movies. The story is set in Movieland, an action film-styled theme park. The game opens on the set of a film starring movie hero and director Captain Blue and an aspiring actress named Jasmine. Just as Blue comes to the girl's rescue at a critical moment in the film, the game's protagonist Joe, dressed as his alter ego Viewtiful Joe, steals the scene. Joe's girlfriend Silvia shows up, greeting Blue and Jasmine and inquiring why they are there. Jasmine explains her ambition to become like Junko, a legendary actress from the past. Suddenly, a group of villains crash the set and make off with a canister containing the reel of Blue's film. Wasting no time, Joe sets out after them. Joe quickly realizes he cannot use his "Movie Energy" to transform into Viewtiful Joe in the real world. To solve this, Blue has Silvia record Joe on a special movie camera called a "V-Cam".
In Double Trouble, there are now 6 extra bars of VFX instead of 5. The Mach Speed and Zoom VFX powers present in the other Viewtiful Joe games have been removed. In addition, players collect V-Tapes instead of V-Films. The VFX bar also seems to drain slightly faster than in other games.
- Slow - Slows down the action to do more damage and begin lock-on. This is Joe's trademark power and has been in the series since the beginning, way back in the original Viewtiful Joe.
- Split - Allows the player to split the screen horizontally and can be used to drop objects on enemies as well as to jump through walls.
- Scratch - Allows the player to shake the screen around to make random pieces of debris fall on dazed enemies.
- Slide - Switches the bottom screen with the top. Slide is similar to Zoom from the first 2 games, but it also gives access to another power, Touch.
- Touch - Can be used to remove small, normally indestructible enemies, such as bats, from gameplay or to flip or turn switches in the background.
- The level Horror World is based on the Resident Evil series, featuring music and enemies from the games, and pictures of villains dressed as Jill, Carlos, Claire and Steve in the background.