Has he ever had a bm in the potty or on the toilet?
What does he do when he has to have a bm?
Does he wear diapers?
Does he have a bm around the same times every day? if so when?
Do you sit him on the potty?
How does he pee? Does he tell you he has to pee or does he go on his own? does he pee in the potty or the toilet?
Thank you for that additional info. You've got to try and get a sense of when he does his bm. Many times if you pay attention you will notice that it's done around the same times each day. Maybe take a calender and mark the times on it and see if you see a pattern.
Also, ask him if he will tell you before he does the bm, even if he's playing, outside, or in the bed. If you notice that he's having a bm after meals, then you can take a few moments after meals to sit him on the potty and give him a little book, toy or magazine and see if he goes. If he does tell you about the bm beforehand, give him tons of praise and love for doing so, even if he doesn't go to the potty at that time. But putting him on the potty after every meal, at least for 10 min (get a timer) will help to start out with.
He's still young, and its not uncommon for them not to be trained until 3, in fact some people will say that 2 is too young, but it's not impossible. In my opinion the pull ups make it too easy. If he goes in his underwear, then you can put him in the tub and let him clean his self off a bit before jumping in and cleaning him, sometimes just having to touch, feel and smell what you automatically usually do, is enough to motivate them to put it in the pot.
Buy underwear with his favorite character on them (batman, spiderman, etc), this works well with some kids, who just cannot bring themselves to soil their hero.
Here are some links
I welcome your thoughts, let me know if you want to talk more