From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
Son Goku met Upa and his father, Bora, the very first time he ventured to Karin Tower during the Commander Red Saga. After his father was killed by Tao Pai Pai, Upa tried desperately to fight Tao himself twice to avenge his father. The first attempt was by throwing a rock at him as Tao was leaving, but Tao easily blew the rock back at Upa which hit him on his head. The second time was by flinging an axe aimed at Tao's head, just as he returned to Karin Tower's base area. Tao however dodges this with ease and then kicks Upa upwards into the air and instantly grabs him with one hand, whilst demanding Upa tell him the location of the Four-Star Ball. After Upa refused to tell him, Tao threw Upa towards the pole of Karin Tower. He was then luckily saved by Goku, who had returned from his training with Karin.
Upa later accompanied Son Goku for a short time during the Fortuneteller Baba Saga in order to recover all of the Dragon Balls so that they could wish his father back to life. He participated in the fight against Uranai Baba's fighters and helped Puar defeat Dracula Man (a kickboxing vampire) with garlic breath. It is interesting to note that when Krillin first met Upa, he though that Upa was a cute girl. He was disgusted when he found out otherwise and apologized to Upa.
After Bora was revived, Upa told his father that he would climb Karin Tower also. It is never revealed whether or not he succeeded.
Upa and Bora later appear once again when Yajirobe brings a beaten Goku to Karin Tower. Upa states he has been taking lessons on how to fight and gives a demonstration.
Dragon Ball Z
Although Karin himself becomes a recurring character in Dragon Ball Z, providing the Z-Fighters with Senzu Beans, Upa and Bora are not seen again except for two instances: once during the Saiyan Saga where he and his father encounter an angry Launch stealing from their tipi, and once more near the end of Dragon Ball Z when they are giving energy for Goku's Super Spirit Bomb to defeat Kid Buu.
Dragon Ball GT
Upa appeared in Dragon Ball: Mystical Adventure.
Upa appeared in Dragon Ball: Advanced Adventure, Dragon Ball: Revenge of King Piccolo, and Dragon Ball Z: Attack of the Saiyans. In his Attack of the Saiyans appearance, he has his Buu Saga appearance, with his Dragon Ball dot-style eyes.
- Japanese dub: Mitsuko Horie (Child)
- FUNimation dub: Kara Edwards (Child, TV series, and Movie 3); Laura Bailey (Child, Revenge of King Piccolo)
- Brazilian dub: Fernanda Bullara (Child)