This movie begins with bubbles and tails.
There we go.
Baron Jaga Butta has funded the creation of an army of Bio-Warriors.
... for the purpose of his revenge!
Meanwhile, #18 has come to Mr. Satan's house to collect on the debt he owes her for letting him win the 25th Tenka-ichi Budokai. (Goten and Trunks are there, too.)
But Satan doesn't have the money just yet.
That's when Baron Jaga's cousin, Menmen, brings Mr. Satan a challenge from the Baron.
And if he refuses, Jaga will reveal to the world that Mr. Satan was a bed wetter.
See, it turns out that Jaga Butta and Mark Satan were friends in 6th grade, and martial arts rivals. But when Mr. Satan defeated Butta, Butta gave up on the Budo altogether. Now that he has become a rich Baron who can afford to fund an army of super warriors, he plans on extracting his revenge by finally defeating Mr. Satan.
And that's the plot of this movie.
At Jaga's home, May Queen Castle, many Bio-Warriors train for their fight.
The tiny Jaga greets his old rival, and Mr. Satan introduces #18 as his number 1 pupil.
Trunks explains to Goten, and the audience, that Bio-Warriors are made with Biotechnology, and Biotechnology is genetic engineering. Of course, genetic engineering is Biotechnology, so you shouldn't be lost.
Jaga tries to turn it into a tournament...
... but 18 decides to take on all the Bio-Warriors in a Battle Royale by herself.
However, Goten and Trunks want in on the action, too!
They recognize the guy on the left from the last movie. (He's important.)
Mr. Satan's "pupils" easily dispatch Jaga's Bio-Warriors.
Jaga takes them into the bowels of May Queen Castle, where his Super Warrior is waiting...
Goten and Trunks rightly freak out.
The prayergiver from the last movie explains how he brought a sample of Broly's blood to Jaga in exchange for a big pay day, after the boys ruined his easy life in Natade Village.
In a move that is shockingly intelligent for Saiyans, Goten and Trunks make to take out Broly before he even leaves his clone chamber.
But they're too late.
Broly has been reborn.
... As a poop monster.
#18 tries to fight Poop Monster in place of Mr. Satan...
... but she's no match for him!
So Goten and Trunks tag-team P.M.
... but they're also no match for him!
Kuririn eventually shows up and saves 18.
And he uses his Kienzan on the Smelliest of Monsters.
But the reborn Legend-smelly Super Saiyan can regenerate now.
... so Kuririn is also no match for him!
That's when Trunks devises a plan. The lab is filled with this messed up purple goop that eats everything alive it touches.
So Trunks leads Poop Monster into it, and Poop Monster dies.
And then he turns into an even bigger, even deadlier Poop Monster.
But no worries, because Goten figures out that purple goop is weak to sea water. So the boys launch a triple Kamehameha into the ocean that turns Poop Broly into a giant statue of Poop for generations to enjoy.