Not always, since you asked how to get more power into a shot, this drives more of your body into it. Make sure you pivot into your shot shifting your weight from one foot to another into the shot before you uppercut. While you are practicing this keep in mind of your partner's right hand, especially that your left hook opens yourself up for it.

You want to lean slightly forward bending your legs as well to get your arm on level to where you're going to punch. Don't bend your knees too much or it'll be harder to move, and don't stay in one spot unless you're trying to set something up. Don't be a sitting duck. You don't necessarily have to step in with your shot unless you're trying to move into a better angle, and keep in mind where you're going to be usually away from their stronger arm, it'll be better if you can make him adjust/turn and you should be ready when they do.

Here's another one you should take note, on the inside find out if they are square shouldered or if they have just one arm forward. Because in the infight if you have just one arm forward, you're limited to attacking with one arm until you shift or adjust your stance. Sometimes it's better to square shouldered such as in this case because you can attack from either fist which is more offensive, while the left side forward would be limited in it's attack and more towards using the left side to defend with. Just some things to think about...