In my opinion, I find it fun to test battle Gym leaders as an example, and as well, when play testing, you don't know what to expect sometimes, a glitch, or a shiny can turn the whole experience around, either freaking out, or spending hours fixing the game in response to the glitch. As well, if you did something really difficult in scripting or ASM, and tested it, and to your joy it works, that's what makes playtesting fun. :D