The top two factors to consider are how competitive the archetypes in the pack are and how many cards players will still need to craft after owning all the cards in the pack
If Diabellstar gets destroyed, it can also bring itself back by sending a card to the grave
UR Ultra Rare Koa'ki Meiru Supplier X EARTH Level 4 [ RockEffect ] ATK 1400 DEF 1600 If a face-up Rock monster you control is sent to the GY (except during the Damage Step): You can Special Summon this card from your hand
The -3 is good but it isn't sustainable
With a massive 3000 ATK and an effect that can add up to an additional 10000, Firewall Dragon Darkfluid can stop any of your opponent's monster effects right in their tracks
Mewtwo transcends those cycles because its appeal is rooted in something deeper than set affiliation or competitive performance: the character's narrative of creation, captivity, rebellion, and self-discovery resonates on a human level that gives its cards an emotional weight most Pokemon simply cannot replicate