We also made this estimate when we first discussed these back in 2017/2018 (see the thread and blog linked by @Dyl earlier), when only one or two copies of each card had popped up
Graded Population Report: Eevee #13 Visualize the distrbution of grades in the chart
This yellow version of Cavern of Souls is not available in booster packs
(2025-04-04) If you cast a spell with demonstrate and both you and an opponent copy it, the opponents copy will resolve first, then your copy will resolve, and finally the original spell will resolve
Pokemon Card Strategy: So as far as strategy goes, I would actually use Double Freeze more than I would use Frost Breath with this card, the reason I would do this is that Double Freeze has the possibility of doing more damage than Frost Breath and more than likely you are going to Paralyze your opponent for the next turn
For a card featuring a Poke Ball, its also pretty beautiful