Sadly, this is also not super realistic
Most require you to have both halves in play, like Brisela, but others may require both halves to attack (like Mishra, Claimed by Gix), or have a certain amount of cards in your graveyard (like Titania, Voice of Gaea)
Lastly, I estimated a winrate as a Bivariate Normal Distribution
Some examples of things to look out for include any artwork which depicts iconic first-generation Pokemon like Charizard and Snorlax, or powerful legendaries like Mew and Rayquaza
The value of X is determined only once, as Formless Genesis resolves
Roiling Vortex costs one generic and one red mana to cast, and is an enchantment with two static abilities and an activated ability