Elmo's still very much a kitten, he might grow out of it, and as he gets older your 2 year old cat might grow to like him more too if he calms down and they get more used to eachother, but who knows what way it will go for sure.
It's probably more of a territorial thing right now, then dominance, since they haven't already been living together for years. Just keep your eye on them. As long as they aren't duking it out daily and one is REALLY scared and always hiding from the other your probably ok.
And make sure the older one has a place to go to have a break from the rambunctious young one.
When my cats play they pin their ears back, when I pet Tage he does that, it's his extreme face of happiness! lol. When they play they let out little struggled quiet mews sometimes, and Tage will ninja kick them, but it's all in play.
Glad to hear your not going to declaw them!
Oh I also wanted to say, just make sure they have plunty of things to do in your home, instead of just picking on eachother, scratching posts, FUN cat tree's, toy's and treats, and have relaxation time with them as well.
Here's also a decent article on the cat site you can read on cat aggression. So you can know more of what to look for in the future. But just remember not all cats will obey these signs of aggression, like the above discribed.http://www.thecatsite.com/behavior/aggression.html