Congrats on the shiny Sewaddle, NecrumWarrior! I think you are the first club member to get a shiny in B/W2.
I recently made it to Castelia City, but haven't explored it much.
I read that if you have Black or White you can use Memory Link to catch N's Pokémon in B/W2 which have the sparkle entrance that shinies have, but aren't shinies themselves. All of their IVs are at 30.