I got an impossible nemesis over spotpass. It's a hard version of one of the hardest bosses in the game. In it's normal form, you should be max leveled if you don't want it to insta-kill you. This version has 9999 magic and 9999 physical defence. All your attacks will do 1 damage and it's attacks can take out half your health. You can only damage it with things like minus strike and phoenix flight. You can use peirce magic defence, but that takes up more than half your support abilities. Not to mention it had 999999 health, and 1023 attack,327 magic attack, 106 evade, and 125 speed It also gives incurable status inflictions that make your party members attack each other until one of them dies. And it looks like this:

It doesn't help that
this weird music is playing durring the battle