How is what the OP is suggesting similar to Galactic Challenges?
OP wants the ability to select the characters on the opposing team, with full omicrons active, and play against friends. OP doesn’t get this from squad arena because there is not enough variety in the opposing squads. OP doesn’t get this from Conquest because data disks change the mechanics in a way that can’t be recreated elsewhere.
Galactic Challenges would see the OP having zero choice in the opposing team lineup, zero omicrons active, facing unrecreatable mechanics as a result of modifiers, playing against the AI, not a friend.
You’ve made it very clear you would like Galactic Challenges back. Attempting to falsify a groundswell of similar opinion isn’t helping your cause.