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Rarest Card
My rarest card would be a Japanese Neo 3 Shining Magikarp (it's got a rarity symbol of three black stars)
After that a 1st edition Base Set Machamp (but I think that that's the card they gave out in starter sets so it's not a rare card at all)
I would recommend an Earth deck with the Machamp/Nidoking from the Royal Guard deck. Cinccino from the Red Frenzy deck is a great colorless stage 1 (especially if you have Double Colorless Energy) Starter decks tend to come with rather crappy trainer content but if you add all the decks together...