Gothitelle: Guardians Rising 54/145
Solosis: Legendary Treasures 74/113 (none really stood out tbh…)
Duosion: Plasma Blast 43/101
Reuniclus: Noble Victories 53/101
Ducklett: Plasma Blast 29/101
Swanna: Dark Explorers 36/108 (with Darkness Ablaze 149/189 as close second)
Vanillite: Next Destinies 31/99 (I like Pokémon with people in the background in most cases. The Darkness Ablaze 045/189 artwork is pretty nice as well.)
Vanillish: Next Destinies 32/99 (I like its goofy expression in this artwork, although I think it’s melting in the sun, haha)
Vanilluxe: Guardians Rising 35/145
Deerling Spring Form: Fates Collide 8/124
Deerling Summer Form: Emerging Powers 15/98
Deerling Autumn Form: Japanese Everyone’s Exciting Battle 004/047
Deerling Winter Form: Japanese Silver Lance 005/070
Sawsbuck Spring Form: Black & White 14/114
Sawsbuck Summer Form: Emerging Powers 16/98
Sawsbuck Autumn Form isn’t available on a TCG card.
Sawsbuck Winter Form: Japanese Silver Lance 006/070
Emolga: Next Destinies 45/99 (with Japanese 025/BW-P promo and Legendary Treasures - Radiant Collection RC23/RC25 as close second and third)
Karrablast: Darkness Ablaze 008/189
Escavalier: Darkness Ablaze 124/189
Foongus: Steam Siege 12/114
Amoonguss: Noble Victories 10/101 (if the set logo wasn’t covering a huge part of the artwork, SM202 promo artwork would have been my favorite instead. Unfortunately it was never released in Japanese and/or without stamp.)
Frillish: Plasma Storm 38/135
Jellicent: Phantom Forces 21/119