dirt bike owners

is registering a dirt bike the same as registering a car? i might be getting a dirt bike on a trade but the dude doesnt have any paper work for it he says the dude he bought it from lost the pink slip.

you have to register it
here in california it either gets red stickered or green stickered.. most new dirtbikes that dont suck balls are red stickered here and u can only ride them certain times of the year at certain places

i know but what im saying is the dirt bike doesnt have a pink slip so can it be registered? without the pink slip?