/opens mouth to point out Rock weakness/
/closes mouth/
Okay then.
Don't worry too much about not finding a place for Butterfree. Shiny pokémon are above average, but individual non-shinies have the potential to be even better.
Have you tried training against the wild pokémon in Route 26? You could go back and forth between there and Victory Road to mix things up...and make sure you've got Cooltrainers Beth, Gaven and Reena and Bird Keeper José on your Pokégear Phone so that, when they eventually call, you can go over and trash them too. They're all on Routes 26 and 27. José's also good to have because he'll occasionally give you a Star Piece, which you can use to fund the Hyper Potions, Full Heals, Full Restores and Revives that'll get you through the Elite Four. You can increase the rate at which these four trainers call you by deleting everyone else except your mom, Prof. Elm and Bill.