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