Like DITTO, it is to breed any pokemon as it doesnt have any RACE or what we call breed. Are there any same pokemon like ditto in BLACK and WHITE for breeding
No. Ditto is the only. AND BEST :D
But, for some moves, you may use Smeargle, which can learn almost any move
No, there is only Ditto.
In B/W you can get a Ditto at the Giant Chasm, which I believe is only accessible after you've beaten the game.