Trainers » Hyper Potion
Can I use Hyper Potion to heal a Pokemon with less than 120 damage on it or if I have less than 2 Energy attached to it?
You have to heal at least 10 damage to play the card. You must also have at least 2 Energy attached to the Pokemon you're healing; if there are less than 2 Energy attached you cannot use this card.
Source: Sword & Shield FAQ (2020-01-24), TPCi Rules Team (2020-02-06)
Errata » Hyper Potion | Trainers » Hyper Potion
The wording of Hyper Potion is now as follows, "Heal 120 damage from 1 of your Pokémon that has at least 2 Energy attached. If you healed any damage in this way, discard 2 Energy from it."
Source: TPCi Announcement (2020-01-09), TPCi Rules Team (2020-01-09)