They are first seen in Six Degrees of Destruction.
Given that none of them were seen inside it in the final battle against the brawlers, it's likely that they all perished when the Alternative was launched from the Motherpalace.
Other guards appear different in the Vestal cities.
- The guards in the Vexos Royal Palace look similar to Emperor Palpatine's Royal Guards from Star Wars.
- The security guards at Beta City look similar to the Team Rocket Grunts from Pokémon.