Despite his age, and the fact his father has been mostly absent most of his life, Rallo acts much like Robert, behaving at times very articulate, yet hormonally charged. He seems to get along fairly well with his mother Donna and has a normal love/hate relationship with Roberta, who at times seems to neglect him, yet at other times speaks to him as if an intellectual equal.
Rallo frequently runs errands for his mother but never remembers to get the change. As a result, he is able to save enough money to buy a 1967 Mustang on eBay. His childlike defiance and hyperactive mischief when being tended to by Roberta was so extreme (including excitedly wiping himself by dragging his bare posterior on the floor) as to scare her away from sex, lest she risk creating anything like him. The fact that Rallo is some sort of child prodigy, makes him an analogue of Cleveland's former neighbor, Stewie Griffin.
With the new arrivals of Cleveland and Cleveland, Jr., Rallo has shown some initial reluctance to accept both into his life, actively insulting them, such as joking about their weight. However, he warms up to Cleveland, who manages to teach him how to handle checking out the girls in his kindergarten class. When Cleveland inadvertently kills the family dog, Rallo is devastated by the loss, but comes to respect Cleveland for all the work he did in trying to "find him" when Rallo thought the dog was merely missing, as well as the effort Cleveland put into trying to be a good parent to Roberta.
Despite being younger than his new stepbrother Cleveland, Jr. Rallo seems to take a more aggressive hand in their interaction, openly insulting Junior. However, this seems to just be Rallo's way of addressing people in general, and not done with any deep malice intended. In fact, their relationship is showing promise of being a decently caring one at this point. In "Birth of a Salesman," both Roberta and Rallo are disturbed by how clean and attentive Cleveland, Jr. is in regards to Donna's parental requests. Initially annoyed at him making them look bad, they become sympathetic when they realize that he never accepted his parents' divorce, and has been doing all he can to avoid giving into his sorrow. Together Rallo and Roberta do all they can to help Cleveland, Jr. let his feelings out and at the same time, they accept him as their brother.
Rallo seems to somewhat value cleanliness and etiquette from houseguests, as demonstrated by his indignant reaction to Cleveland and Cleveland, Jr., not making their beds after staying the night with the Tubbs family in the pilot.
He was an antisemite, as discovered in "Ladies' Night". After befriending a Jewish senior citizen in "Murray Christmas", even going so far to celebrating Hanukah with him, it appears that he no longer is. His antisemitism is contradicted by his affection toward his stereotypically Jewish teacher, Mrs. Hadassah Lowenstein, to whom he declared, "You mean the world to me. The world to me!"
In one episode, he becomes racist towards white people after learning of the history of slavery in the United States. Rallo then go on rants to kill and harm white people, but changes his stance once he sees that the Krinklesac family are not racists, are not responsible for owning slaves and actually enjoy many of the same activities and foods as himself.
His favorite meal consists of fish sticks and Tater Tots, and, before his stepfather moved in, he sat at the head of the dinner table.
Donna mentions in "Brotherly Love" that Rallo takes diarrhea medicine.
In the episode "American Pranksters", Cleveland asks Donna why his name is Rallo. Donna replies to that question by stating it was from "That guy from Sanford and Son" (referring to Rollo Larson).
He appears briefly in "The Splendid Source". While eating dinner with his stepfather's visiting friends, he responds to Peter Griffin's remark about a black Jesus colored on the wall with a fat joke.
In It's A Trap!, Rallo Tubbs is cast in the role of Nien Nunb.
While in Italy in "Boopa-Dee Bappa-Dee", Peter attempts to use the guide on the television remote, turningStewie into a host of past and present Animation Domination characters including Rallo.
Rallo moves to Quahog with the rest of the family in "He's Bla-ack!". He also joins in Thanksgiving dinner with the neighbors at the Griffin home in "Turkey Guys" and in "Peter's Sister", as well as Peter's backyard picnic in "Hot Pocket-Dial".
He is voiced by Mike Henry.