Notes & Combos
The meta in UB4 is very saturated with Suicune and Electric/Oricorio nonsense. I endorse using Suicune Grenjinja to make it to Master Ball with ease. I'm inherently anti-meta, so using Silvally Giratina was a challenge for myself, and I don't recommend it for the regular player who wants to have fun in the sense of getting high win streaks.
In the climb I used a little bit Electric and a little bit Guzzlord. Both can't keep up with the consistency of the Suicune engine, to be frank. Silvally Giratina takes time to perfect, but it counters both Oricorio nonsense and Suicune, only when the starter is right.
To win, you can't always commit to your starter. The tool cards are used to deal self-infliction without using energy to attack, and at least deter while you set up a backrow Giratina or Silvally. Against Suicune, it is best to keep your bench a low count. Thing is, against those decks, taking precautions won't guarantee a win but it raises your odds with a well-timed Mars or Cyrus on a hurt Grenjina. A +1 in the hand every turn is too good and Greninja chipping away is so effective. It really deserves the S tier.
Gio and Barb are the flex spots I can consider changing. A Poké Comm can replace a late Giratina for a Silvally piece, maybe, a PCL can keep your Giratina alive an extra turn. I would like to continue testing the deck to make it most effecient. Including Pichu didn't work out for me, but maybe it would for you, the reader. Ya'll read my reports?