Picked up a stray last year & he's now bullying me.

He needs attention, positive reinforcement. He doesn't need to be scared or punished. Having a rescue is like having a child. You cannot simply do things only on your schedule or when you feel like it. They need to be treated differently. They need more attention, and discipline (which is not the same as punishment). Structure. If he's overweight you need to change his diet and exercise him more, take him for walks and play ball (not just when you feel like it).

It's totally unfair to compare him to any other dogs. He's his own dog with his own needs and personality, including his own baggage. You need to step up your game.