Are we splitting when we lose control of the kid or when the avoidance is actually over and screen goes black?

Does anybody know why sometimes damage to bosses becomes ridiculously low, like 1-8 points, despite very high characters attack? I tested it on 2 eng ROMs, BST one from 1999 and the newest 2.08v. The results are the same: Dragon is untouchable when I first get access to the Ark, but becomes normal after Beryl destroys Silver Kingdom, despite no attacking character stats are changed. Also, the last Hell Destiny fight is impossible if I bring the team of certain senshis but is ok with another group. Crystal Tokyo is much worse though, idk what to do to overcome this problem. This bug/mechanic is so weird and basically the only thing that keeps me away from speedrunning this game.