Gaea's Protector

• WWizards of the Coast2018-04-27
  Official Ruling
  Only one creature is required to block Gaea’s Protector. Other creatures may also block it, and are free to block other creatures or not block at all.
• WWizards of the Coast2018-04-27
  Official Ruling
  If each creature the defending player controls can’t block for any reason (such as being tapped), then Gaea’s Protector isn’t blocked. If there’s a cost associated with blocking Gaea’s Protector, the defending player isn’t forced to pay that cost, so it doesn’t have to be blocked in that case either.
• WWizards of the Coast2018-04-27
  Official Ruling
  The defending player, not you, chooses which creature blocks Gaea’s Protector.

Rulings via Scryfall