Trying to recreate Zedaf's Proximity map in 1.13, but ran in the problem of making opposing team members visible on the same island. First, I thought to make an execute
/execute unless @a[team=blue,team=red,x=-200,y=30,z=-600,distance=..10] run effect give @a[team=blue]
/execute unless @a[team=blue,team=red,x=-200,y=30,z=-600,distance=..10] run effect give @a[team=red]
but that would be detecting someone on both teams. The main question is how do I make it where if two separate teams are in the same are in the same area then no more invisibility for the people in that area alone, but if only one team is present then they remain invisible.
I can only find answers with the
testfor function which does not exist in 1.13.