Ah, I remember when I was trying to catch Uxie. If it would flee I'd just restart my save and try to catch him again. One of the times I reset my save, he ended up being shiny. I fucking shat a brick trying to catch it and ran out of literally all of my poke-balls. Fuck you shiny Uxie. Fuck you.
Arena Trap ftw. Correct me if I'm wrong, but don't Uxie, Mespirit, and Azelf show up on the map when they run? I thought they worked like GSC's Legendaries...
And if they do work like GSC's legendaries, they should keep their shiny/non shiny status whether they run or not.