Okay -- my experience is that until somewhere near age 4, you have to get up, walk over, and "help" them "listen." Everytime. Follow-through is not the strong suit of a 2 or 3 year old. Even after 4 -- it seems like they get easily distracted and need "coaching." But its definately better.
But I don't think its reasonable to expect a 2 yo. to simply do what you say, unless you are also prepared to stand up, walk over, and guide them through it.
I 2nd the idea of coming up with "strategies." I used to work in mental health, and we came up with written "strategies" for coping with behavior issues in our adult clients. The strategies were written with the client's individual needs and temperment in mind by the people who were most experienced with that particular client, then reviewed by the entired staff, and adhered to consistantly by everyone for a period of time. And then re-evaluated for effectiveness.
I know it sounds like overkill -- but DH and I have used this approach with our kids. Brainstorming a strategy for a specific behavior problem, writing it up formally, reviewing it together to see that we are on the same page -- and then applying it consistantly for 2 weeks to see if it helps. (Without resorting to less constructive measures within that time frame.)
It helps us to have a plan. "This is what we're gonna do when he hits -- and we're gonna do it evertime, and we're both gonna do it... and in 2 weeks we'll talk about whether it helped or not."
I know I've said it before, but I'll say it again. Its kind of awful from a 2 yo. perspective to know that sometimes you are gonna get hit, but never knowing when or why. Having the possibility of being hit by either of his parents hanging over his head is really *NOT* going to help him behave. Its just going to confuse and upset him, and set him on edge -- which will in turn affect his behavior for the worse. I *do* know you are doing your best though.