Both bars use the same coordinates. Something that is in a different place depending on whether it's for a user's Pokémon or an opponent is the shininess star, so you could have a look at that to see what to change.
As you can see, both of the battle boxes use the same class when they are loaded up and called up. There are some differences in the two though, like the player box has @showhp=true and @showexp=true. So if you were to create conditional branches to check for those (hence distinguish from player and opponent boxes) you could tweak the positions of the HP bars to your desire.