Throughout the game, there are many Archetypes that dominated the scene at one point or another, taking advantage of a new mechanic that hadn't been countered yet
Doctor's companion (You can have two commanders if the other is the Doctor.) Legendary Creature - Human Advisor Donna Noble Soulbond (You may pair this creature with another unpaired creature when either enters
Jhoira of the Ghitu Jhoira is a great leader that should be flexible enough that each Jhoira deck plays out differently, right
So knowing this about the first two Pokemon in this line and looking at this specific Porygon-Z, the main reason you would want to use this card in a deck is for its Digital Reboot move, the reason you would want to use this move so often is to be able to reuse an Ability from let's say a Stage 2 Pokemon every single turn, like Aggron from Dragons Exalted (if you're playing in the expanded format) where you can use its Toppling Wind Ability to discard the top 3 cards of your opponent's deck every single turn and hopefully be able to win the game that way
When Pokmon: The First Movie arrived in theaters back in 1999, moviegoers received one of four exclusive cards as an added incentive