Base Set Pikachu - Trying not to put more than one card from the same era on this list, but you cant deny Base Set Pikas cultural importance and relevance
Yes, not one, but two, which rarely happens
5 Dark Magician (Ultra Rare) - $400 Dark Magic Attack

Mega Chandelure ex), Mega Chandelure ex SIR, 3 IRs (Dhelmise, Manectric, Bastiodon), 1 UR trainer (Heroic Bomb) Round 2, Box 1 36 packs (full box): 9 ex, 4 IRs (Silvally, Goldeen, Dhelmise, Toucannon), 1 UR trainer (Brave Bangle), and the gold Mega Darkrai ex MHR (118/081) , plus 3 shiny energy Round 2, Box 2 14 packs (partial): 3 ex, 2 IRs (Manectric, Bastiodon), 2 shiny energy Round 2, Box 3 36 packs (full box): 9 ex, 4 IRs (Silvally, Slowbro, Toucannon, Armarouge), 2 full art cards, 2 shiny energy We've now folded in two large community openings (136 packs) to broaden the sample to 253 packs and three full boxes: Community box 36 packs (full box): ~9 ex (Mega Delphox, Mega Zeraora, Wailord, Mega Slowbro, Mega Excadrill), 5 IRs (Toucannon, Fomantis, Goldeen, Slowbro, Feebas), 2 full arts (Morpeko ex, Misty trainer), and the coveted Mega Darkrai ex SIR (114/081) the set's top chase, pulled from a single box Community opening 100 packs (~2.8 boxes): ~25 ex (a run of Mega Chandelure ex), ~11 IRs (Fomantis, Slowbro, Goldeen, Armarouge), 3 full arts (Brave Bangle, Mega Darkrai ex UR, Rampardos), ~5 shiny energy and notably zero SIRs and zero golds across all 100 packs Pull Rate Data: 253 Packs This section reflects a combined sample of 253 packs our own 117 packs plus two large community openings spanning three complete 36-pack booster boxes

5 Gyarados XY60: XY Promos (Staff Promo) $360.55 Hard To Find Gyarados is probably the coolest-looking of these average cards, and the Ancient Origins stamp alongside the Staff distinction gives you a clue that this card is unusual
For example, let's say you're playing a deck that revolves around a certain Pokmon, but you don't have that Pokmon in your hand to start with