This will be all the information I've found or know. The guide will be too useless because I wrote it. Thank you in advance for your attention!
Many of the materials are taken from the wiki, which is quite outdated.
I will update the information as much as possible.
Please let me know if I made a mistake, and I will make the necessary changes.
・Cast Member
Cast Member Complete the story's opening sequence in any mode.
• Get into prison. It's simple: you need to complete the first story levels in single-player or co-op.
・Seasoned Performer
Seasoned Performer Complete the first four finales in any mode.
• Complete Chapter 4 in single-player or co-op.
・Hats Off
Hats Off Get a letter grade in all eight finales in any mode.
• Complete Chapter 8 in single-player or co-op.
・Take A Bow
Take A Bow Complete an encore level in Story Mode.
• Complete 1 time trial level in any chapter. Time trials are located to the left of the final level of the chapter. Each chapter has 3 levels.
・Crowd Pleaser
Crowd Pleaser Complete all Encores in any mode.
• Complete all Time Trial levels in any chapter. Time Trial levels are located to the left of the final level of a chapter. Each chapter has 3 levels.
・Solo Star
Solo Star Get a letter grade in every level (except Encores) in Normal Solo Story Mode.
• Complete the single-player story on normal difficulty.
・Coop Star
Coop Star Get a letter grade in every level (except Encores) in Normal Co-op Story Mode.
• Complete the multiplayer story mode on normal difficulty.
・Insane Solo Star
Insane Solo Star Get a letter grade in every level (except Encores) in insane solo story mode.
• Complete the Single-Player Story on Mad Difficulty. Mad Mode is a stronger version of Normal Mode, except there are no checkpoints and you only have one life per level.
・Insane Coop Star
Insane Coop Star Get a letter grade in every level (except Encores) in insane co-op story mode.
• Complete the Multiplayer Story on Insane difficulty. Insane mode is a stronger version of Normal mode, but without checkpoints and with only one life per level. In the Multiplayer Story mode, if your partner dies, the level restarts.
・Nail File Cake
Nail File Cake Free a fellow prisoner.
• Purchase one prisoner for 10 emeralds. Available in the Gift Shop.
・Black Marketeer
Black Marketeer Get yourself a cool new weapon.
• Purchase your first weapon for 5 Golden Balls. Purchase from the gift shop on the second floor.
・First Time Trader
First Time Trader Make a trade with someone.
Trade items with someone in the gift shop in the special room on the second floor.
・Armed and Dangerous
Armed and Dangerous Collect all the weapons in the Gift Shop by unlocking or trading.
• Collect all weapons in the game. You can purchase weapons from the cats on the second floor of the Gift Shop, by trading with other players, or by purchasing them on the Market.
・Jail Breaker
Jail Breaker Free 50 prisoners in the Gift Shop.
• Purchase 50 prisoners, each costing 10 emeralds. Available for purchase in the Gift Shop.
・Social Butterfly
Social Butterfly Collect all the prisoners of one head shape.
• Collect all captives with heads of the same shape. You can check this in the exchange room or on the starting room screen.
・Freedom Hero
Freedom Hero Free all the prisoners in the Gift Shop by unlocking or trading.
• Collect all captives. You can check in the trade room or on the start screen. You can purchase from the Gift Shop, by trading with other players, or on the marketplace.
・Virtuoso
Virtuoso Get an A++ in 10 levels.
• Complete 10 levels with an A++ grade. I recommend completing this achievement in the first chapter.
・Secret Finder
Secret Finder Find a secret level.
• Complete a secret, simplified level. You can find one in each scene in certain levels. The very first secret level appears in Chapter 2, on the second level.
・Secret Hat Hunter
Secret Hat Hunter Collect 10 Golden Hats.
• Collect 10 golden hats. They appear randomly at any point during any campaign level, including game modes.
・Prison Food
Prison Food Get eaten alive.
• It first appears in Chapter 2, on level 8. Find it and run up to it, and it will do everything else itself.
・Consolation Prize
Consolation Prize Die enough times and we give you a prize.
• Achievements are random. If you die too many times, you'll eventually earn this achievement.
・Traitor
Traitor Kill your teammate 50 times.
• Kill your friend 50 times with rolls, slides, and other moves.
・Chicken Toucher
Chicken Toucher Play with the Behemoth or someone with this achievement in an online game.
• Play with a BattleBlock Theater developer or a player who already has this achievement.
・The Professional
The Professional Be on the winning team in 100 arena matches.
• Win 100 Arena games in any mode.
・All Around Joe
All Around Joe Be on the winning team in one arena match of every mode.
• Win at least once in Arena in all modes.
・Deadly Performer
Deadly Performer Get 100 kills.
• I think there's no need to explain this.
・Melee Master
Melee Master Successfully use every melee attack move.
Use all melee attacks (You can view them in the settings. All attack combinations are there. This achievement is easiest to complete with a joystick):
• Jump, then Normal Attack (D) / A, then X • D / X • ← or → + D / ← or → + X • ↓ + D / ↓ + X • ↑ + D (someone must be above the character) / ↑ + X (someone must be above the character) • Strong Attack (A) near someone / B near someone • Weapon (A) away from someone / B away from someone • ↓ + A / ↓ + B • Throw (W) / RT
・Weapons Master
Weapons Master Use each weapon successfully.
• Weapons are purchased from the cat in the gift shop on the second floor, or on the marketplace and through exchanges.
・Theater Critic
Theater Critic Complete 10 user-created levels in a single Featured Story playlist.
• Download a community map (featured by the developers), play 10 levels, and rate it.
・Theater Manager
Theater Manager Download and host a game of user-created levels.