With only 8 SR types versus 10+ in standard sets, your odds of pulling any specific SR are roughly 50% better than in a typical OP booster box
I'm not the user responsible for putting together the Kanto TCG, but I think I know what's going on here
Like most Pokmon cards, the value of Venusaur-EX 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 (XY)
This would be good even if it could never transform, and transforming it is actually very doable, since it spits out Wizard tokens and is a Wizard itself
Additionally, these cards appear only in English in all languages of Play Boosters and Collector Boosters
Overall, The Mechanist feels like an upgrade to Sai, Master Thopterist