The 20th Anniversary reprint of Dewgong was shared on Twitter today. Thanks to Vincent C. for the translation! Compare it to the original English Base Set card to see the difference. The 20th Anniversary CP6 set will be released in Japan in just a few days on September 16th.
[W] Super Deep Dive: Heal 40 damage from this Pokémon and switch this Pokémon with 1 of your Benched Pokémon.
[W][C][C] Take Down: 90 damage. This Pokémon does 20 damage to itself.
Weakness: Grass (x2)