Its included here because people mention it, not because its the best approach
Not every deck you play against is going to be playing Dragon type Pokmon, so depending on the mathcups, Giratina EX could really be a strong play in your decks as long as the deck can support it energy wise, which might be a bit of a struggle, although the Hydreigon deck can do it with one of the Blend Energy
So as long as the card revealed isnt a land (with its subsequent 0-damage trigger), you are likely to draw cards from it, as long as its not too damaging
Grave Pact and Martyr's Bond When you control a Grave Pact, opponents find themselves sacrificing creatures with great regularity
They do damage then either have you switch that Pokmon with one of your Benched Pokmon, or have you remove that Pokmon from play in some way, effectively keeping that Pokmon out of danger