So, I caught a Minun in the Dream World (in Black 2). But when I checked it's summary it said it's name was Minum. But then, when I was playing Emerald I caught a Minun and it said it's name was Minun. If you check here it says Minun! So which game is correct? Did Nintendo change it?
No Nintendo didn't change it. You might have accidentally changed it nick name without realizing it. I know I've done that before. If not that, then it must have been a glitch.