Like most Pokmon cards, the value of Gastly depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (HSTriumphant)
Silumgars Scorn with Dragons is a pipe dream without strong card draw
2 Trainer card from a Lizardon Mega Battle card is the most expensive out of all the cards that made this list
One of the best white creatures, Sunny's a big body that returns a cheap permanent from the graveyard to the battlefield ( any permanent, not just a creature), and if our foe doesn't want our Sun Titan to keep generating value every turn, they'll have to spend at least a card dealing with it ASAP
Play Boosters are perfect for Limited play and fun to open, with a possibility of Art cards, alternate art, special frames, and additional Rares and/or Mythic Rares