Turns of battle? Here’s where it’s determined (Oh, edit, brave effect is determined inside the subroutine calls, fyi). The animating, though, takes place somewhere else. I assume it just animates based off of the battle buffer.
I edited this routine to write the numbers to use in the battle screen in the display hack part of my Modular Battle project, but I could probably rewrite this system to be a bit more adaptable as well. Or check for vantage/provoke specifically. It doesn’t seem too bad. Though keep in mind that the Battle Buffer is limited to 7 slots(without repointing the battle buffer pointer), with the last having to be 00 00 80 00, so I’d imagine that would have to be reallocated/the &pointer repointed.