Update on this from last week:
Calwings posted... All right, I decided on a playthrough: I'm gonna beat Pokemon X with only bugs. Started with Froakie just to use as an HM mule later, caught a Weedle and a Scatterbug on route 2, added a Caterpie in the forest, and I'm off to the races. I'll probably do my 2nd playthrough of Z-A after I finish this.
I'm already almost done with this playthrough. I just got the 8th and final badge, and my team consists of Crustle, Masquerain, Flygon, Drapion, Durant, and I can't believe I'm about to say this...
Illumise. I never expected this silly little firefly that I originally caught as a team filler after the 1st badge to become the unexpected MVP of my playthrough. There were so many battles that I won because Illumise crippled an opponent's strong Pokemon with paralysis from Thunder Wave and/or attack drops from Charm or Struggle Bug, giving one of my other bugs a chance to switch in safely and set up. Plus, I was under the extra restriction of not using items in battle, so she was also a cleric in major battles with Wish. Needless to say, I have a new appreciation for Illumise after this.
Have you guys ever had a Pokemon you didn't like/appreciate before become an unexpectedly good part of a playthrough like I just did with Illumise? If so, which Pokemon was it, and in which game?