buy one piece tcg booster box TCG: The Time of Battle (Japanese) such as Mihawk from OP01 and Doflamingo from OP04 One Piece Card Game Royal

You can obtain the Incineroar ex (2-Stars rarity) card by opening Celestial Guardians: Solgaleo from Celestial Guardians set

Although Rock Throw doesnt do a lot of damage, he does have fairly high HP and his other move, Harden, could be quite useful from lighter attacks

You can obtain the Typhlosion ex (4-Diamonds rarity) card by opening Ruler of the Skies from Ruler of the Skies set

Both the English and Japanese Base Sets are very valuable, but some early promos and other cards sit atop the list of the most expensive Pokemon cards

Not that useful at the beginning of the game, but helpful in a pinch in the mid to late game stretch