Starter deck upgrade format. Take 2 copies of any 1 starter deck and for ST07 onwards (excluding advance decks) make a deck using 25 (including eggs) cards from these decks + any other cards (normal deck building and ban rules apply). For ST01-ST06, the same rules apply but only 16(?) cards from the deck need to be used and for advance decks, again the same rules apply but 40(?) cards from the deck need to be used.
