They're all unlocked after completing the second film story but after that they have to be bought while walking around in the main hub port area. (except for Bootstrap Bill Turner).
Characters required for this achievement :
*Bootstrap Bill Turner -- (Main Character) Found on The Dutchman’s Secret in Dead Man’s Chest.
*Maccus -- Buy for 15,000 Studs. (Outside the Taverns) Found on The Dutchman’s Secret in Dead Man’s Chest.
*Clanker -- Buy for 15,000 Studs. (Inside the movie clip tavern) Found on The Dutchman’s Secret in Dead Man’s Chest. Unlock Code: ZM37GT
*Jimmy Legs -- (In the movie clips tavern) Buy for 15,000 Studs. Found on The Dutchman’s Secret in Dead Man’s Chest. Unlock Code: 13GLW5
*Koleniko -- Buy for 15,000 Studs. Found on The Dutchman’s Secret in Dead Man’s Chest. (Walking along the level boards pier; with Davy Jones)
*Davy Jones -- Buy for 500,000 Studs. (Walking along the level boards pier.) Found on the Maelstrom in Dead Man’s Chest. Unlock Code: 4DJLKR
*Wyvern -- Buy for 15,000 Studs. (On the Beach swim towards the screen) Found on The Dutchman’s Secret in Dead Man’s Chest.
*Angler -- Buy for 15,000 Studs. (Inside the movie clips Tavern) Found on The Dutchman’s Secret in Dead Man’s Chest.
*Hadras -- Buy for 15,000 Studs. (In front of the lighthouse) Found on The Dutchman’s Secret in Dead Man’s Chest.
*Crash -- Buy for 15,000 Studs. (Inside the movie clip tavern) Found on The Dutchman’s Secret in Dead Man’s Chest.
*Penrod -- Buy for 15,000 Studs. (In front of the lighthouse) Found on The Dutchman’s Secret in Dead Man’s Chest.
Note; The characters that walk around in the main hub will have a black circle above there head. You'll need to buy the character and all characters if you want the Parley! Achievement. Don't forget to hit these characters a few times to buy them. Or you can put in cheat codes if you like doing that doesn't effect the achievement.
If your having trouble trying to find these characters most of the Dutchman crew like to end up on the Beach in the main Port just swim towards the screen. Hope this helps.
For all other characters check the Parley Achievement Guide Here:
http://www.xboxachievements.com/forum/showthread.php?t=55886...Credit for video GameGuideCentral