The Assassins from Universe 9 were a group hired by Sidra and Roh in order to attempt to kill Goku and Frieza, Team Universe 7's competitors, before the Tournament and thus stop them from being able to participate in the Tournament of Power.
After being hired by Sidra and Roh, the Assassins head to Universe 7 and arrive at Fortuneteller Baba's Palace, they ask that Goku and Frieza come out to fight. Goku requests information about who they are but their leader, who resembles a bulldog, arrogantly states that he cannot say anything.
Frieza immediately shoots the leader through the shoulder, causing him to plummet into the water. The Assassin horde gets cocky and tries to persuade Goku and Frieza to engage them in battle, rather than make their way to the Tournament of Power. Frieza instead responds to this as an opportunity for a warm-up.
Frieza transforms into his Golden form where he goes on a psychotic rampage, slaughtering many of the Assassins with an improved Emperor's Death Beam. Some of the remaining Assassins then try to take Fortuneteller Baba hostage, however this amounts to nothing as they are stopped by Goku's quick intervention.
The leader then recovers, while still having the shoulder wound, and is revealed to have divine powers given to him by Sidra which he uses to attack Frieza. Although Frieza effortlessly destroys the first two projectiles, he gets hit by the third one, however he recovers and throws it at Goku.
It is unknown if their souls were erased when Universe 9 lost the Tournament of Power as they were killed in Universe 7.