In the Challenger's Bonus, he is the playable character.
She tells the crew something in the Shroob's language and shot down the Kooopa Cruiser with a Shroob missile. Baby Bowser was flung away from the Kooopa Cruiser in the impact into his castle.
Eventually, he realized that the Mario Bros. When the Mario Bros. He then left to the other side of the peak after Kamek had given him some "evil" milk. After the Mario Bros. Soon after, Baby Bowser and the Mario Bros. Inside giant Yoshi, Baby Bowser, along with the Yoshis already eaten, was put inside an egg. Baby Bowser then ate all of the Yoshi Cookies and got sick. Later, Baby Bowser went to Thwomp Volcano to build a new castle, where he met his future self, Bowser.
After a little argument, Baby Bowser and Bowser teamed up, not knowing the other ones identity, against the Mario Bros. They ended up being beaten after the battle and flung into the sky by a Thwomp, where Bowser ended in a time hole and Baby Bowser ended up on top of the Shroob Mothership. He showed up again after the Bros. He was then turned into a Shroob Mushroom. Baby Luigi's tears later turned him back to normal.
During the second phase, Big Baby Bowser attacks by breathing fireballs at Yoshi, advancing from in the background. If Big Baby Bowser gets too close the ground is destroyed, instantly defeating Yoshi. The player must grab the Giant Eggs that Baron von Zeppelins carry onto the stage and throw them into the background at Big Baby Bowser to knock him back. After enough hits, he simply charges forward, and after seven hits, he is defeated, returned to his normal size and knocked out.
Afterward, Kamek reappears and vows revenge before flying off with Baby Bowser. Yoshi then sprints up to the Stork and Baby Luigi , freeing them both and allowing the Stork to deliver the babies to their parents. It's possible to defeat Big Baby Bowser even when the platform is gone. If done, he falls down, and Yoshi falls, landing on a platform where Baby Luigi and the Stork are. Yoshi will notice Kamek, who flies off.
Then, the rest will be back to normal. To make matters worse, he turns the entire island into a pop-up book. It's up to a bunch of Baby Yoshis to stop him. Baby Yoshi has to hit Baby Bowser with Bob-ombs while the prince is riding his " pet " and knock him off. He then recites a "poem" about how he's the king, and intends to smash Baby Yoshi and thus demands the latter say goodbye. The battle is then on the ground where Baby Bowser shoots fireballs, throws bombs, and sends shock-waves; Yoshi has to hit him a few more times to beat him.
After being beaten, Bowser surrenders, and allows the baby Yoshis to have the Super Happy Tree back, rationalizing that the fruit tasted horrible to him anyway, before being carried out by his Toadies while sobbing. During the events of Yoshi's Island DS , Baby Bowser is at his castle when his future self shows up to kidnap the star children and gain control of the universe.
Baby Bowser is ironically abducted by the future Kamek from the past Kamek and brought to Bowser's Castle. When he realizes the circumstances, he insults his grown-up self and his plan, calling him an "old geezer. As Baby Bowser plummets, he swears revenge and once he lands, he yells into the sky in a futile attempt to remind his older self that they're one and the same.
Baby Bowser then realizes that he has just landed on Yoshi and is stoked to get a ride from him. Baby Bowser is then playable for the remainder of World 4 ; as the Nintendo Power Player's Guide puts it, he shows up to "kick some major enemy butt, of course!
Once Big Guy the Stilted is defeated, Baby Bowser leaves Yoshi's group in an attempt to hitch a ride from the future Kamek as he flies off to report to the adult Bowser. However, Baby Bowser loses his grip and falls off of Kamek's broomstick.
Baby Bowser later rejoins Yoshi's group, along with Baby Wario who he had been fighting with over treasure , when they reach Bowser's Castle.
He eventually betrays them and attacks Yoshi and the other babies, believing they're after his treasure. The fight goes much like the previous one, but faster. Yoshi beats the little prince and Kamek takes him away, leaving the group to the future Bowser, who is angry at what Yoshi did to his younger self.
He is then eventually defeated. At the end of the game, Baby Bowser falls off Kamek's broom and lands on a barge carrying his treasure, now claimed by Baby Wario; another argument between the two young misers inevitably ensues. Presumably, Baby Bowser is taken back by the past Kamek. After a 7-year hiatus, Baby Bowser appears in Yoshi's New Island as a main antagonist alongside Kamek, and his older self later in the game. In this game, he plans to turn Egg Island into his vacation home, so the Yoshis, as well as adventuring to rescue Baby Luigi, go out to stop Baby Bowser's plan.
At the end, the scenario is similar to the original Yoshi's Island. He is once again awaken from his slumber, only to crush and kick Kamek out. He soon notices the "familiar green donkey" and proceeds to try and ride Yoshi again. He is the penultimate boss of the game in a two part battle reminiscent of his battle in Super Mario World 2 , though the second part of the battle where he once again becomes the giant Mega Baby Bowser  thanks to Kamek is more similar to the battle with Giant Bowser in New Super Mario Bros.
His voice in this game is a more baby sounding voice of his future son , and is evidenced further from the second phase of the battle. After he is defeated, and before the stork and Baby Luigi are rescued, his future self appears out of nowhere, making Yoshi and Baby Mario battle him. Then, Yoshi suddenly appears and Baby Bowser starts the battle with him. Yoshi must throw a yarn ball provided by one of three red Shy Guys that periodically fall from the top of the screen at Baby Bowser, then ground-pound him, and repeat this three times to defeat him.
After Baby Bowser is defeated, Kamek later uses the power of the Wonder Wool to make him transform into Mega Baby Bowser , where he once again has a similar voice to his future son. In his debut, Super Mario World 2: Yoshi's Island , Yoshi must enter the castle and work his way to Bowser's bedroom, which is filled with toys.
When Kamek tells Yoshi to hand over Baby Mario , Baby Bowser wakes up and tells them to be quiet because he is "sleepy". Kamek is instantly filled with fear.
Baby Bowser stomps on Kamek before noticing Yoshi. Thinking Yoshi is a donkey, he tries to ride him several times but Yoshi knocks him out. Kamek returns and "helps" Baby Bowser by turning him into a giant, destroying most of the castle in the process. As a giant he appears more like his grown up self.
After a long, epic battle Bowser is reverted back to his baby self and is unconscious. Kamek is horrified and calls Yoshi a meanie before flying off into the night with Baby Bowser. Yoshi then frees Stork and Baby Luigi and the stork flies away with the babies into the night.
The giant version of him is the biggest boss in the game. Even though he is the final boss he is not the main antagonist, as Kamek is. He is also one of the two only characters who talk in the game. In Yoshi's Story , Baby Bowser becomes jealous of the Yoshi's happiness, so he steals the Super Happy Tree and casts a spell to turn the entire island into a story book.
The Yoshi's then set out to revive the Super Happy Tree. The last page of the story book is Bowser's Castle. While riding on Yoshi he can breathe fire, which can defeat enemies and light up torches, as well as performing a lot of the moves that an egg can do destroying? At the end of world 4, he gets taken by Kamek , but rejoins the babies later on in Bowser's Castle However he betrays the other babies when they reach the end of his castle.
The other babies and the Yoshi's succeed in defeating Bowser and rescue Luigi.
— Baby Bowser, Mario & Luigi: Partners in Time. Baby Bowser (called Prince Bowser by his minions), also known as Bowsie or Baby Koopa, is one of the two main villains in the Yoshi franchise, alongside Kamek. He was designed to be the infant self of Bowser. Although not related to him, Kamek is mainly responsible for his child rearing. Baby Bowser, as the name implies, is a younger version of Bowser. He is often confused in design and name with Bowser Jr. He has appeared in various Yoshi games, usually as the end boss. Baby Bowser was the baby form of Bowser that appeared in SML's MALSADA Season 3 Episode 3. Baby Bowser was raised by Margaret. He lived with Baby Mario and Baby Luigi. His mother didn't feed him, so he made a deal with Baby Mario that if Baby Bowser would help, Baby .