To ensure supply is similar, I compare cards of the same set and rarity
The card game would come shortly after the video game's initial release, but only came to America at the end of 1998

Advanced Search Sets Random Syntax Accorder's Shield Ashnod's Coupon Black Lotus Blacker Lotus Bone Saw Cathar's Shield Chrome Mox Claws of Gix Crimson Kobolds Crookshank Kobolds Dark Sphere Darksteel Relic Delif's Cone Everflowing Chalice Fountain of Youth Gustha's Scepter Herbal Poultice Indicate (playtest) Intervention Pact Jack-in-the-Mox Jeweled Amulet Jeweled Lotus Kite Shield Kobolds of Kher Keep Lion's Eye Diamond Lodestone Bauble Lotus Petal Mana Crypt Memnite Mirrored Lotus (playtest) Mishra's Bauble Mox Amber Mox Diamond Mox Emerald Mox Jasper Mox Jet Mox Opal Mox Pearl Mox Poison (playtest) Mox Ruby Mox Sapphire Orb of Origin (playtest) Ornithopter Pact of Negation Pact of the Titan Paradise Mantle Phyrexian Walker Rograkh, Son of Rohgahh Shield Sphere Slaughter Pact Spellbook Spidersilk Net Summoner's Pact Tormod's Crypt Urza's Bauble Urza's Contact Lenses Welding Jar Zuran Orb

With decks like these, its hard to mulligan a hand that has all your colors of mana, since youre too likely to get a non-functional six-card hand
Rainbow Pokemon cards are valuable for many reasons, mainly due to their rarity and aesthetic appeal
Speaking of big creatures, if you are the rare green deck that doesn't have any, Khalni Ambush drops from great to medium or even bad, but since big creatures are more or less green's thing, it's hard to imagine too many green decks that won't get value out of the instant-speed fight spell