Lots and lots of training, i dont see why you would want to do it, it would take ages and make the rest of the game boring, plus at that point you havent got much materia to be gaining experience as well either

To get the Carob Nut fight a monster outside Bone Village called Vladorakos, you have to steal the nut from it, the best greens to feed chocobos are Sylkis greens, you can buy these from the Chocobo Sage, keep feeding the chocobo until you are told its stats are maxed out