However, I have evolved my Taillow, Torchic, Ralts, and Snorunt all the way. Haven't gotten Beldum completely evolved yet. Been playing though Black 2 with my shinies and a few others.
Yes it will sparkle if it is a wild encounter. It will not sparkle if it is from an egg. Even if it did not sparkler, most pokemon have a huge color difference and should be spotted fairly easy, but yes it does still sparkle if it is an encounter and it will sparkle if you use it in battle.
Ok and can I find a shiny by just walking aimlessly in a cave or tall grass?