Recovery from Leech Seed, HP gained/lost from Pain Split and moves like Giga Drain all give information. As it stands, you have to remember / write down your HP before these moves occur, which isn't very convenient; albeit it isn't unreasonable, but convenience is ultimately a big part of PS.
Solution 1: Make special player only text detailing the important information giving elements of HP draining effects.
Leech Seed: Show the player who used it how much HP they recovered from it and the opponent what % of their HP recovered.
Pain Split: Show what % both Pokemon were at before and the change in HP of your own Pokemon.
Giga Drain etc: Show the HP gained to the user and the % gained to the opponent.
Solution 2: Allow players to view previous turns in the battle the same way spectators can, while displaying the exact HP their Pokemon were at.
Solution 1: Make special player only text detailing the important information giving elements of HP draining effects.
Leech Seed: Show the player who used it how much HP they recovered from it and the opponent what % of their HP recovered.
Pain Split: Show what % both Pokemon were at before and the change in HP of your own Pokemon.
Giga Drain etc: Show the HP gained to the user and the % gained to the opponent.
Solution 2: Allow players to view previous turns in the battle the same way spectators can, while displaying the exact HP their Pokemon were at.