In Super Robot Wars A Portable, there is a scenario boss that can join you later and when you manage to Ace him(get 50 kills and you get a unique ability for him) he gets ridiculously bulky the less health he has. That sounds helpful but that ability carries over back into his NPC Boss form in NG+ and I’ve heard it soft-locks the game.
Only way to avoid it is to know that information and don’t give him kills.
Good thing I learned about this trigger event >!but I still accidentally got the blacksmith during a couple of my NG+ run. In the Dark Risen DLC, they extended the Gransys Innkeeper’s beloved meter so long you will not accidentally be locked to him!<.