Kabuto is can be obtained from the Dome Fossil, if you have one then if you are playin Pokemon HG/SS then you would take it to Pewter City and talk to the man to the far right of the Muesuem and he will extract the Pokemon Kabuto. In Diamond, Pearl and Platinum you can extract Kabuto from the Dome Fossil at the Meusem in Oreburgh City, talk to the man to the right at the front desk. If you are playing B/W then you would go to Nacrene City and I am pretty sure it would be at the far right of the Meusum there.
If you are playing the GBA Games then I can't help you.
Hope this helped :D :D :P!