i assume i need to shoot the enemy until they're blue and then i can swap; pretty solid, but then there's no need to have a cooldown of 5seconds or so.
swapping with enemies that are perched high up seems to be the only utility this mechanic has. other enemies just walk towards you so there's no benefit in swapping with them even if the swapping worked with them. also can't swap with the boss, but then why would i want to.