You need to have a friend who you can trade with to use this cheat. start with a mudkip and only train him and you should beat the first gym easy then at dewford catch geodude and train it to like level 16 or 18 by beating wild pokemon. then beat the gym trainers and use geodude against the gym leader and when it faints finish him off with mudkip or if it evolved then with marshtomp. then go to slateport and buy like 5 super potions and train both pokemon to level 25. then you should be able to beat May if you dont on the first time train some more. then forget about marshtomp because the next gyms are electric, fire, normal, then bird. rock is super effective against all but normal and normal can barely hurt rock so you should win easy. your graveller should be so strong during this time you take out all trainers easy. if you dont beat May the second time just train some more but graveller should be so strong you beat her easy. then after you beat the bird gym you should trade graveller to a friend who will trade it back because it will be a golem when it goes to your friend so make sure your friend will give it back. your golem should be so strong you beat everybody else easy.

Note: make sure you are only training your graveller during this time or it wont be as strong.