Have you tried talking to Wattson again? This might advance you to the next part of the quest.
Whoops I solved it sorry, I just had to talk to plusle while I was standing right next to the rod. I just thought it weird because I was a few paces away when I was able to get minun to attach to the other rod. That inconsistency combined with my character calling the plusle "minun" made me think there was some sort of glitch, ie the game thought that the plusle was the other minun.