Best Fitness Friends

"Kaley: We're here to talk about... Beef: Health! Kaley: Beauty! Dieter: And a personal enrichment system known as Perfect You! Beef: Get bouncy and smooth hair! Kaley: Teeth that don't fall out! Dieter: Muscles that quiver like whippets! All: That's right, you can have all of these and more when you sign up with... Best Fitness Friends!''"

- Best Fitness Friends

The Best Fitness Friends (also known as the Brute Force Federation, BFF for short) are the main antagonists in the Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey side mode, Bowser Jr.'s Journey. Posing as pharmaceutical reps with a cure for the blorbs, they help Fawful infiltrate Bowser's Castle and aim to take out the Koopalings to stop them interfering with their own plans.

The trio consists of Dieter, the thin, bespectacled and tie-wearing ranged fighter who throws cards in battle and acts as its leader; Kaley, a short, perky and supplement-addicted bird-like creature who takes the role of their air fighter; and Beef, the aptly-named rotund and silent member of the group that serves as their melee fighter.

The Brute Force Federation was Beef's idea for their name; Kaley had wanted the group name to be the Cutie Coalition.

History
During the events of Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey, the Best Fitness Friends infiltrate Bowser's Castle on Fawful's orders. When inside, they offer to sell the Koopalings Skeletone Formula:D, saying it is a cure for the blorbs (which they then demonstrate on one of the nearby Goombas). However, they then reveal they do not have any more of the formula, and that the Koopalings will need to buy the recipe and make it themselves if they want any more.

This turns out to be a ploy to leave Bowser's Castle defenseless, as well as provide the Friends with a chance to get rid of Bowser Jr. and the Koopalings. They do this by secretly following Bowser Jr. and the Koopalings around the kingdom, attempting to dispatch them and steal the ingredients in the process. After seemingly dispatching Ludwig and scaring Iggy off a cliff, they reveal their true identity as the "Brute Force Federation".

The trio also reveals that the Skeletone Formula:D has a secret power that they plan to utilize - mind control, which is made possible by mixing the formula with poison from a Malodorous Fibbian to create Malatone Formula:X. Said power is then used to brainwash Morton and turn him against Bowser Jr., with the BFF plotting to eventually infect all of Fawful's army the same way as part of a plan to overthrow Fawful and take control for themselves.

From there on, the BFF encounter Bowser Jr. and the Koopalings a few more times. In one of these, they actually succeed in defeating the group, but are thwarted by Captain Goomba, Captain Boo, Captain Shy Guy, and Captain Koopa Troopa before they can dispose of them. They also try and stop them by sending out waves of brainwashed minions.

Eventually, Bowser Jr. and co. track down the group in Bowser's Castle, where they face them in a final battle. After defeating them both individually and as a group, the Best Fitness Friends merge into a giant Malatone-fueled monstrosity with incredible powers. At the start of the battle, it creates dark clones of the Koopalings to act as its troops. It can disable some of Bowser Jr.'s Captain Commands, and temporarily blow some allies away from the battlefield. It fights as a Melee type, and its Special Skill is Piercing Projectile in which it fires a massive laser from its mouth that damages all allies at once.

Bowser Jr. and his troops defeat them for good and get back the Skeletone, as well as the castle, in the process.

Technology

 * Skeletone Formula:D
 * Malatone Formula:X

Profiles
Dieter ''The brains of the BFF. He will achieve his goals by any means necessary.''

Kaley ''The professional cutie of the BFF. At least, she usually talks in a cutesy way. But is that how she REALLY is...?''

Beef ''The brute force of the BFF. He's silent, but just one attack will leave you reeling.''

Best Fitness Friends The ultimate BFF form, realized when all members join together and take Malatone Formula:X.

Trivia

 * Each BFF member's primary color and to a certain extent physical appearance represents one of the three trooper types in the game. Dieter is yellow-denoted, carries cards, and is a Ranged type, Kaley is blue-denoted, a bird-like creature, and a Flying type, and Beef is red-denoted, muscular, and a Melee type.
 * According to a Nintendo Dream interview, the Best Fitness Friends are the same species as Midbus, but their relationship with him has soured.