My son has a kawasaki engine on a cob Cadet the plug keeps fouling out cleaned carb but it did not do anything for the problem

Is it fouling out with oil or is it fouling out with soot and fuel deposits ?

it seems a little oily but smells like fuel

Check your oil to see if its over full or has fuel in it .

I changed the oil and tried to fire it up spark plug is fouled after about 5 pulls

You may need to disassemble the carb and soak it for a few hours in carb cleaner then put a rebuild kit in it. Also are you getting spark to the plug ?