Flummoxed Cyclops

• WWizards of the Coast2020-01-24
  Official Ruling
  Once two or more creatures your opponents control have attacked, Flummoxed Cyclops won’t be able to block, even if all but one of those attackers leave the battlefield before its triggered ability resolves.
• WWizards of the Coast2020-01-24
  Official Ruling
  In a game using the shared team turns option (a Two-Headed Giant game, for example), Flummoxed Cyclops’s ability triggers if two or more players each attack with only one creature.

Rulings via Scryfall