Notes & Combos
I build this deck last season but i think it's more easy to use now since the Solgaleo usage reduced drastically. From UB3 to Masters was 43 wins and 22 losses with 66.2% of Win rate.
Gengar's bother attack is a key part of this deck but Giratina is the finisher. While you keep attacking with Gengar, your bench is safe and your hand too, at least from Mars, since Red Card still keep 3 cards, i think this is not a threat.
The formula is simple (while not easy): Charizard, Incineroar, Solgaleo, Guzzlord, Buzzwole when take 50HP from Bother, they can't use Lillie, PCL or Erika, that's when Giratina came to finish with 130 atack.
Like any Rare Candy deck, it's prone to brick more than others decks but here you have Giratina. The perfect start is Gastly + Giratina on bench. While you have Giratina on your bench you never attack or attatch energy do Gastly or Lele, it goes always to Giratina, when you need to use Gengar, just use the energy on the turn you need to attack.
Some games you don't even need Gengar, just Giratina to ramp trough every eevolution, Greninja, Silvally e etc. While you keep bothering your opponent active pokemon, Greninja shuriken can't pull you with Cyrus.
You can ask yourself: why not Sylveon Ex or Gengar Ex? I didn't test neither but something good could came out idk. The key part is Giratina turn 1 or at least turn 2, more than that things go difficult fast.
About cards, all of them have key parts, the only one that i think it could be changed is the tools or maybe Tapu Lele (lele is most used to try to counter Charizard and most of the time is used as a shield while Gengar or Giratina ready come). Leaf and Mars are essential cards. While you keep bothering your opponent, their supporters cards keeps maxing numbers in his hand that's when you Mars them (idk you guys but i only use Mars when the opponent already has at least 1 point and it seems to work like 90% of the time. The perfect usage of Mars, for me, is when 2 mons already died and Giratina is coming as active and boom, your opponent only has 1 card).