Predicting whats going to see the most play throughout that many months of different formats is basically impossible, but thats the fun of this
The most uncommon card in the Evolving Skies set is the Rayquaza VMAX #218 and the Umbreon VMAX #215
Like most Pokmon cards, the value of Gimmighoul depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Surging Sparks)
Im far more wary of dead cards in hand by way of HOPT mismanagement, but the consistency provided is undoubtedly a benefit
A lot of what Ive learned about this connection between gambling and Pokmon cards comes from various YouTube videos and insights from my gambling therapist
If you think about it, it has the disadvantage of being unable to attack, and the effect is unstable, so it's quite a difficult monster