Kaley, Dieter and Beef turned around in fear and saw Boom Boom and red skin and steam coming out of his eyes and ears, he screamed, "YOU MURDERERS!"

Kaley asked fearfully, "D-do we know you?"

"YOU KNOW VERY WELL WHAT DID!"

Dieter asked, "What are you talking about?"

"POM POM IS DEAD BECAUSE OF YOU!"

Wendy said, "And we are going to avenge her!"

Beef said, "RUN!"

They ran for their lives, but Boom Boom and Wendy were hot on their trail, the goons ran everywhere they could, but they were unable to lose them. Wendy was slowly getting exhausted from chasing them, but Boom Boom did not get tired and carried Wendy on his shoulders as he continued flailing his arms and screaming death threats at them.

The Best Fitness Friends ran to Bowser's Castle to hide, they locked the door and barricaded it, but Boom Boom punched it open like it was nothing and yelled, "GET READY TO DIE!"

This got the attention of the Koopalings, who all converged on the scene after hearing Boom Boom, Morton asked, "WHY BOOM BOOM SCREAM? MORTON'S EARS HURT."

Iggy asked, "What's going on?"

Bowser Jr. blurted, "I think I know, it's those BFFs, they are back!"

Larry groaned, "Them again?"

Ludwig said, "What did you guys do now?"

Roy answered, "They killed Pom Pom, remember? I think I overheard Boom Boom mentioning them and yelling that he wanted to kill them all."

Wendy beckoned her brothers and Junior, "Perhaps you'd be interested in helping us take them down?"

Morton said, "MORTON WANT HELP WENDY."

Lemmy said, "Count me in."

Bowser Jr. scoffed, "Nah. I got better things to do."

"Junior, you said you would treat us better, didn't you?"

Roy said, "Yeah! Or was your promise a fib?"

"Ok, fine. How do we defeat them?"

Boom Boom roared, "BEAT THEM TO DEATH! USE ALL OF YOUR BRUTE STRENGTH!"

That was exactly what they did. They all showed zero mercy, punching their faces, kicking their crotches, scratching and biting them to the point of bleeding profusely. Morton's hammer dealt lots of damage to their bodies, Lemmy's balls gradually disfigured their faces, Roy's Bullet Bill cannon blew them up and Iggy's Chain Chomps bit and bit, causing festering wounds.

They allowed Boom Boom to deal the final blow, he pulled out a bunch of sharp weapons out of his shell that he had packed when looking for the BFFs and used the sword with the longest and sharpest blade, he swung it at maximum speed, slicing off Kaley, Dieter and Beef's heads in that order and in one swing. With Fawful's cronies decapitated, Boom Boom ate their heads one by one and watched as their blood spilled on the floor, saying, "Blood for blood, your debt is paid."

Bowser Jr. and the Koopalings cheered, celebrating their victory over the even worse bad guys that were the Best Fitness Friends.