What kind of gloves should I wear for heavybag and focus mitt training?

As a former golden gloves boxer who has dabbled in MMA, I think that if you're getting sloppy with 16oz gloves on the heavy bag then you should continue to use them until you're not sloppy anymore. I trained 10 five minute rounds on heavy bags with 16oz gloves when I was preparing for a fight, and by the 8th round I could barely hold my hands up. That's when the training really starts to make an impact. It's easy to throw clean punches when you're fresh, a lot harder when you're dog tired. The heavier gloves might be doing you a favor. But if you're looking for a combination of speed and protection, I think getting some 10oz competition grade gloves might be a good idea. They're much quicker, offer the protection you need, and won't be a huge shock when you drop them for the grappling gloves.