BT6-104 Parabolic Junk This card has 0 cost and can gain memory regardless of the opponent's status, limiting designs for future cards
Not essential, but useful
I know you can't really transfer data from another game in the GBA era, but come on

Attack!" When Goodwin activates that monster's effect, he announces "Guiding Light can revive a Level 1 LIGHT monster!" When Goodwin Summons "Oracle of the Sun", he announces "Come out, Oracle of the Sun!" Most of the time when Goodwin attacks with that monster, he announces "Oracle of the Sun attacks!" When Goodwin activates that monster's effect, he announces "I activate Oracle of the Sun's effect!" When Goodwin Summons "Power Tool Mecha Dragon", he announces "Power Tool Mecha Dragon!" Most of the time when Goodwin attacks with that monster, he announces "Power Tool Mecha Dragon attacks!", followed by "Full Metal Demolition!" When Goodwin activates that monster's Trigger Effect, he announces "By equipping an Equip Spell, Power Tool's effect activates!", followed by "I draw a card!" When Goodwin activates that monster's Quick Effect, he announces "Power Tool's effect moves an Equip Card!", followed by "Equip Grappling!" When Goodwin Summons "Supay", he announces "The Tuner Monster, Supay!" Most of the time when Goodwin attacks with that monster, he announces "Attack, Supay!" When Goodwin activates that monster's effect, he announces "I activate Supay's effect!" When Goodwin Summons "Supay, Duskwalker", he announces "Let's go, Supay, Duskwalker!" Most of the time when Goodwin attacks with that monster, he announces "Supay, Duskwalker

If a really good hand isn't drawn then hope there is something to turn through the deck like Magical Mallet or the other card advantage pieces