In this Magic The Gathering format, all cards must have been printed at common/uncommon rarity in a set or product. Common/uncommon promo cards are only legal if the card meets that qualification.
If a common/uncommon version of a particular card was ever released on Magic the Gathering, any version of that card is legal in this format.
Other than that, the usual rules for constructed decks apply:
Minimum of 60 cards in the main deck (There is no maximum size for main decks) Up to 15 cards in your sideboard, if used No more than 4 of any individual card in the main deck and sideboard combined (with the exception of basic lands)