Here is the full list of all 18 Poker Night 2 achievements. It takes around 15-20 hours to unlock all of the achievements on Windows.
Achieve a lifetime balance of one million dollars.
Win GLaDOS's bounty item.
Activate the Portal deck, felt, and chips simultaneously.
Unlock all decks, felts, and chips.
Win Brock's bounty item.
Win Sam's bounty item.
Activate the Army of Darkness deck, felt, and chips simultaneously.
Activate the Venture Brothers deck, felt, and chips simultaneously.
Win Ash's bounty item.
Purchase a drink.
Activate the Sam & Max deck, felt, and chips simultaneously.
Win Claptrap's bounty item.
Win a tournament.
Activate the Borderlands deck, felt, and chips simultaneously.
Purchase a felt.
Purchase a deck.
Purchase a set of chips.
Win a hand.