Doubtless, if you're a pokemon fan you've seen this one coming. Pikablu!
Apperently, if you talk to Oak in R/B/Y a hundred or thousand times, he gives you a Pikablu/Pikatwo/Pikayou/Pikawho/Pikashoe/Pikaglue/Pikapoo/Pikamew/Pikaclue/Pikagoo/Pikaloo/Pikaboo/Pikamoo/slap in the face/whatever(quote http://glitchcity.info/docs/myths). I actually believed this once.
Why it Doesn't Work? Edit
There's a simple answer: there's no secret Pikablu/Pikatwo/Pikayou/Pikawho/Pikashoe/Pikaglue/Pikapoo/Pikamew/Pikaclue/Pikagoo/Pikaloo/Pikaboo/Pikamoo/pokemon. Zilch, zip. The only secret pokemon in R/B/Y is mew. (see Mew Glitch)You can still try. Oak might be in a good mood and give you a slap in the face.
http://glitchcity.info/docs/myths: some glitch myths here