Gengar H9 has a powerful attack that either burns or confuses the enemy Pokmon depending on the coin toss, but more importantly, it has the Pok-Power: Manipulate, which allows the player to place a basic Pokmon from the discard pile onto their bench and flip three coins to determine the amount of energy cards the player can attach to said Pokmon from the discard pile
Playing cards which can self-sacrifice or cycle wherever possible is a solid start and is usually a sidegrade at worst the precon already features several strong options in this vein
It perhaps doesn't help that Zacian and Zamazenta never really resonated with many collectors when it comes to Legendary Pokemon
Still, if you find the right time to do it, Bahamut, Warden of Light does a good job of ending the game for you
This specific card's sale to a private collector shattered all previous records
Include a classic Death and Taxes theme to make things difficult for your opponents, and you should be able to get the most out of Ardenn and Rebbec very quickly