A 'Bad Smoke' is directly attacked with one player's minion but he has enough LP to stand the attack. Then the player attacks with Hickman. Is this 'Bad Smoke' also able to 'Block' that damage? One main rule is that every minion can block one time during the attack phase.
Minions cannot be directly
attacked in combat. An attacking player merely chooses which opposing player
they wish to attack along with which of their minions will be attacking that player. The defending player is the one who chooses which defending minions block which attacking minions.
In later sets we changed the wording to "absorb" when effects like Bad Smoke or Vulko prevent damage from reaching the player. This is different from electing a minion to block during combat and so can be done in addition to assigning them to block.
In your example, should a player attack you with two minions (Alton Hickman plus another), you could certainly assign Bad Smoke as a defender against the other minion, letting the damage from Alton Hickman be absorbed via Bad Smoke's In Play
Edit: Or you could choose to block neither minion and simply absorb the damage from both with your Bad Smoke. The only advantage to assigning Bad Smoke to block during combat would be to use an effect that triggers when being assigned to block.