Answer 1

Imafraid not you will need to transfer from gen IV
In pearl diamond platinum gible is found in wayard cave and in hg ss in safari zone locations
here

Answer 2

If your Pokemon white game is connected to Pokemon global link you can test your luck and try and find one of them in Pokemon dream world, in Pokemon dream world iv got all kinds of Pokemon for my Pokemon black game including larvitar and stantler.

P.s. and if you hurry you can get a mewtwo through mystery gift and get a arceus (think I spelt that right) through the global link too.

Answer 3

You could transfer from past generations, or global trade. I got my gabite by trading a snivy. (what luck!)