The distribution of different rarities has changed many times over the years, most recently with the 2024 Murders at Karlov Manor set
While the number of cards produced for each winner of the contest is unknown, PWCC estimates that between 13 to 100 copies of each winning design exist - making them among the rarest Pokmon cards ever made
Spell cards possess a crucial role in Yu-Gi-Oh!, often being utilised as quick support to boost the strength of your combos and key monsters and to turn the tide of battle
Double-sided versatility: Both sides are erasable, giving you twice the creative real estate
Forbidden, Limited, and Semi-limited cards can be cards of any type, and the Yu Gi Oh banlist typically contains numerous Monster, Monster/Effect, Monster/Fusion, Monster/Link, Monster/Synchro, Monster/Xyz, Spell, and Trap type cards
Yugioh Duel Monsters manages to have plenty of those, but I wouldn't call them obscure or forgettable