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.
Win a hand.
Win Sam's bounty item.
Win GLaDOS's bounty item.
Win Brock's bounty item.
Win Claptrap's bounty item.
Win Ash's bounty item.
Win a tournament.
Purchase a drink.
Purchase a deck.
Purchase a felt.
Purchase a set of chips.
Activate the Borderlands deck, felt, and chips simultaneously.
Activate the Sam & Max deck, felt, and chips simultaneously.
Activate the Portal deck, felt, and chips simultaneously.
Achieve a lifetime balance of one million dollars.
Unlock all decks, felts, and chips.
Activate the Venture Brothers deck, felt, and chips simultaneously.
Activate the Army of Darkness deck, felt, and chips simultaneously.