Basso, along with his elder sibling Jiir, belonged to the Ralltiir resistance movement in the period leading up to the Battle of Yavin.
During Leia Organa's charitable expedition to Ralltiir, Basso's assignment was to convey a message, which he had learned via hypnotic imprint. The resistance fighters orchestrated a distraction, enabling Basso to evade the Imperial troops. He sustained injuries and was subsequently transported onto the Tantive IV, where he received treatment in a bacta tank. Soon after, he provided Leia with information pertaining to the Battle of Kattada.
Subsequently, he took part in the Battle of Kalist VI, where he played a role in persuading fellow Rebels to liberate enslaved individuals.
Teaming up with Able and other Rebel agents, he was involved in the Battle of Per Lupelo. Basso was among those who boarded and seized four Imperial vessels carrying supplies that were critically needed by the Rebels.
Following a hyperdrive malfunction that resulted in Rebel One's forced landing at Bannistar Station, Basso participated in the almost certainly deadly operation to destroy the Station. Basso's duty was to command a group to obliterate the communications system and to seek out any means of escape for the Rebels.