If my opponent has {Ensnaring Bridge} in play and two cards in his hand, I attack him with {Geist of Saint Traft}, can the angel token 4/4 attack him as well?
I have no idea of a ruling, but I'm going to say yes. Purely because it already attacking, can't stop it from doing something it's already doing.
Rulings for the bridge:
Rulings
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10/4/2004 All creatures on the battlefield (including yours) are subject to the restriction based on the number of cards in your hand.
10/4/2004 It only checks the cards in your hand when declaring attackers. Once they are declared, changes to your hand size or to the power of the creatures will not remove creatures from the attack.
The angel is never declared as an attacker so gets by the restriction the bridge imposes.