Baby

Personality
very childish in the way he goes about planing his take which is why vegeta was so shocked to have his body took over which could ended in his death if pulled off wrong but due to this nature of his it was done in a way it made hard and unpredictable as well as being cunning to be knowing this part of his personality and how vegeta would react if did it normally and being overconfident to the extent of his death being caused by such arrogance

History
Getting created by a co project which involved dr raichi and the tuffle king as well as well as multiple other doctors in this project that also had their own creations for their cause  to get revenge on the saiyans for the genocide on their race called the Tuffles. Baby was drifting in space for years on end until finding earth and later creating Dr.Myuu to mutilate the events of the saiyans for his benefit until his body could mature enough to put up a fight and later on after the death of Dr. Myuu which he based him off the scientist that created him being dr raichi as the king of the tuffles himself. he went on to steal vegeta's body and almost killing the saiyans until goku unlocked super saiyan 4 which was mistake made by him due his childish and egotistic nature in fighting and slipped due to such losing control over bodies of z fighters and getting by beat goten in a fist fight in a attempt to escape cause he knew he did not have the skill needed to defeat him  as he was to childish and did the experience needed to do such and as well  years later in a different timeline getting revived by Oren  and Karmin along with Hatchiyack for a plan to gain revenge on the saiyans at a later point

Power
being stronger than goku in gt in his mutated version of vegeta's body even going as far to stomp goku while in super saiyan 3 and even being a equal in his super saiyan 4 form but lefted vegeta's body to not die and him normally being comparable to goten in base in gt as a adult who killed him with not much effort due to his skill as a combatant comparative to baby in his base form despite having comparable power