Like most Pokmon cards, the value of Koga's Grimer depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Gym Challenge)
Just like the Amber and Amethyst Starter Deck, the cards shown on the front of the box are guaranteed to be Foiled
Discard all Fire Energy cards attached to Blaine's Charizard except 1
Some are hidden, making them really difficult to track
But if, you have reliable sources for die rolls, and you were going five color dice, why not slot in Dee Kay, Finder of the Lost
Afterburner Expert Auntie Ool, Cursewretch Boartusk Liege Boggart Ram-Gang Boom Scholar Feral Animist Goblin Anarchomancer Ground Pounder Grumgully, the Generous Hungry Spriggan Ignoble Hierarch Joyride Rigger Jund Hackblade Mudbrawler Raiders Ol' Buzzbark Owlbear Shepherd Redshift, Rocketeer Chief Rulik Mons, Warren Chief Scarwood Goblins Scuzzback Marauders Scuzzback Scrapper Shattergang Brothers Slimefoot and Squee Steamflogger Service Rep Swirling Spriggan Tattermunge Duo Tattermunge Maniac Tattermunge Witch The Space Family Goblinson Vexing Shusher Wort, the Raidmother Zhur-Taa Goblin