A couple of things: I take it this is not an in-kind replacement, otherwise you would just buy a new version of what you already have. With that assumption, I think you are asking the question the wrong way; the model of boat is practically irrelevant in buying an outboard bracket. You are buying the bracket to fit the motor.
What bracket fits a 9.9 Merc outboard? There are two big factors to consider: is the outboard a two stroke or a four stroke?; and, how long is the shaft?
Four stroke outboards generate more torque than two stroke engines, and weigh more for a given horse power than two strokes. Most manufacturers rate their brackets for either two stroke or four stroke engines. There are dozens of threads on this and other sites debating whether it is appropriate to put a relatively light four stroke engine on a two stroke bracket that is rated for much heavier engines. I'm not an engineer, nor do I play one on TV, so I will not opine on the subject. But, when replacing the bracket on my Oday 23 a couple of years ago, I did a lot of research and spent a good deal of time on the phone with a very knowledgeable customer service rep at Garelick, one of the biggest names in brackets. He gave me chapter and verse on why I really needed a four stroke bracket for my new four stroke outboard. I decided to go with the four stroke rated bracket, which raised other issues.
My new outboard was a long shaft, just like my previous two stroke outboard. I figured it would be easy to just mount the new bracket on the old "spacer" block (that wedge on the transom that places the outboard far enough away from the transom to tilt it out of the water) and be done with it. Not so fast Popeye. Turns out that the "throw" on the new bracket (it's range of movement) was different than the old bracket. So the entire mounting structure of spacer and bracket had to be moved down about two inches, meaning drilling new holes in the transom. And the base of the new bracket was wider than the spacer, which meant I had two choices: build a new spacer, or make an "adapter" plate so the new bracket would fit on the old spacer. I went with option two.
So before you buy a new bracket, understand that unless you are going with a direct replacement of what you already have, chances are this is going to involve more than just bolting the new bracket to the transom. My advice: when you buy a new bracket that is appropriately sized for your engine (2 v. 4 stroke, weight), duct tape it to where you would mount it. Make a cardboard template of your engine, and "mount" it to the bracket. See if you can tilt the engine the way you need to. Make sure the prop will be appropriately deep. You will know quickly how big a job it will be to make that bracket work.
Yeah, what Mstern said. Luckily we have a great Mercury Outboard dealer in my neighborhood. I would find such a place and ask them for advice. It's important that the outboard be easily accessable and comfortable to use. Placement is key. Is your engine compatable to using a remote throttle and gear shift? I have used that system on several boats of that size. Seems like overkill, but actually make it safer and more comfortable. Good luck on your set-up.