Advice for potty training the world's most stubborn 4-year-old?

I was in this same situation with my son. I tried giving him things,taking things, being nice, i never did the cold turkey...didnt want pee on our bew carpets or couch and we didnt do the pullups because i think they are the same as diapers only more expensive and when i bought him these he said they were big boy pants..which they are not. One day i wad just so frustrated with him so i said i was going to take him to see the doc because maybe there was something wrong with him and maybe they would have to give him a big needle in his . It was Soo mean i know but the next day he was potty trained. Fully potty trained!!! Even at night. It has been about a year and he has had a hand full of accidents which i think is great. What works for some kids doesnt work for others so hang in there. Btw my doctor always saud worst thing u can do is pressure her too much. He said he never sent anyone to kindergarten in diapers. Good luck :)