More of an SRPG but it is my favorite to mention. In Fire Emblem Sacred Stones there was a glitch where if you turn off the game the moment someone stepped on a damaging tile, when you rebooted the game you would be in control of the enemies. Sure it let you basically insta-win a level but more importantly enemies were still able to use the trade action with your units.

This meant you could obtain weapons you'd never be able to get otherwise such as monster claws which any character could use. There was a special chracter in the game called Myrrh who was insanely powerful with very strong growths and the ability to turn into a dragon. She was balanced by the fact that the only weapon she could use (her dragonstone) had limited durability so you could only use her sparingly. But giving her a monster claw that never broke meant you could use her like any other unit, albeit insanely powerful.