X and Y have turned me into a filthy casual

I want to play though a soulsilver rom but cant stand just blasting though with one pokemon but i am too lazy to level multiple pokemon

I am aware that i am the worst kind of person however is there any way to get exp share like X and Y in SS/HG

since its a rom i can use AR but i cant find any codes im looking for, anyone have ideas

also i know that i can use EXP modifiers but i would prefer to get normal EXP but have it shared to all pokemon