You don't know what we've been through...
A few months ago, I was playing Diamond. I was participating in a challenge called the Champion challenge where I was using only Pokemon that Cynthia used. Don't worry, this isn't some weird challenge topic. I got to the Galactic Building in Eterna City, and had a Spiritomb and Feebas, which I traded in, and a Budew that wouldn't evolve.
I made it all the way to the top of the building and fought Jupiter. Needless to say, I lost. I rest my game, and after a couple tries, could not win. So I decided to back track all the way to the GTS to check my Budew's friendship via Pokecheck. Once I returned to the Eterna Building, everyone was gone, including Jupiter and the Bike Salesman, as if I had won the fight against Jupiter. I was so dumbfounded that a bug like this could exist. I have yet to test it a second time since then, since I haven't restarted my Diamond.
Has anyone else ever encountered this, or would like to test it? I will be resetting my Diamond pretty soon, but it will be for another challenge.