Sightless Brawler

In a Two-Headed Giant game (or in another format using the shared team turns option), Sightless Brawler (or the creature it enchants) can attack with a creature controlled by your teammate, even if no other creatures you control attack.

Unlike other Auras, an Aura with bestow isn't put into its owner's graveyard if it becomes unattached. Rather, the effect making it an Aura ends, it loses enchant creature, and it remains on the battlefield as an enchantment creature. It can attack (and its {T} abilities can be activated, if it has any) on the turn it becomes unattached if it's been under your control continuously, even as an Aura, since your most recent turn began.

You still control the Aura, even if it's enchanting a creature controlled by another player.

If a permanent with bestow enters the battlefield by any method other than being cast, it will be an enchantment creature. You can't choose to pay the bestow cost and have it become an Aura.

If you control more than one creature that can't attack alone, they can both attack together, even if no other creatures attack.

On the stack, a spell with bestow is either a creature spell or an Aura spell. It's never both, although it's an enchantment spell in either case.