J.O.
I would start with one thing at a time, otherwise it may be too overwhelming having to give up everything he loves at the same time. First get him to the point where he will drink straight cow's milk out of a bottle. Once he is completely off formula and has been drinking milk from a bottle for a couple of weeks then switch one bottle a day to a sippy cup. I switched out the morning bottle first because my daughter always woke up thirsty. After a week or 2 switch another bottle feeding to a sippy cup. The most important thing is to not give in and give him a bottle once you've eliminated it. Even if he refuses the sippy cup don't worry he won't dehydrate and it won't drastically effect his health. He needs to know that a sippy cup is his only option. You may get some tears or a tantrum but you can't give in. If you eliminate the bottle gradually the transition will be much easier on everybody and soon he won't even miss the bottle.