Baby Bowser is a character appearing in Mario & Luigi: Partners in Time.
Baby Bowser can do almost everything Bowser can do. Baby Bowser spits fireballs and when he is with Bowser, he can throw a mushroom in the air to heal Bowser and himself. He can also hammer Bowser while he is in his shell form.
Overall, Baby Bowser is a spoiled brat. He can get very angry sometimes, and at other times he lacks common sense, and is also a tad unintelligent and dimwitted, for he didn't know who his older self was and neither did Bowser .
In his first battle:
In his second battle: