@KLAIRI2002 In their profile picture it shows the leader of their Squad Arena team. You can’t borrow anyone for use in squad arena - you can only use characters from your roster.
You cannot see what they have set for their squads in dark side, light side, cantina, and mod battles - but whichever unit you can borrow from them in that game mode is the leader they had set the last time they manually attempted it.
Fair warning: most players who have a Galactic Legend rarely battle manually - most of their battles are simmed, so the last time they manually set a leader may have been years ago, but that is the leader available for you to borrow.
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