First, I'm not aware of a 16 grain pellet available for a .25, and second, WHY? If you want a 16 grain, a smaller form factor like a .22 or a heavy .177 would be much more appropriate and give better ballistics. In a .25, the drag and ability for the wind to blow it all over the place. Lastly, you buy a .25 for hitting power over a .22. That hitting power is lost with lighter weights.
So, accuracy loss, hitting power loss and probably stability loss.
But if there's a why that makes a 16 grain pellet work better for you, it'd be interesting to understand. Why are you considering a 16 grain? The reason might make all the difference in the world. My answer is based on my experience, and maybe I'm missing something?