Batman Inc
At the beginning of the game, choose an opposing character for all charaters using this team ability. While any character using this team ability is on the map, whenever the sum of all modifiers applied to that opposing character's combat values is greater than +1, the sum of all modifiers is instead +1.

I'm trying to understand how this works. Let's say the opposing character has their movement modified by +1 and their attack +1, do I or the opposing character's controller choose which value is modified?

Basically it translates to, that character can't have any stat raised above +1, but all of them potentially could be +1.

Ahhh, I see. What a weirdly worded ATA, huh?

It functionally works, because you never reference more than one stat at a time, and modifiers only matter when you need to reference a stat, so the +1 only affects the stat being referenced at this moment.