Here is the full list of all 47 Knowledge is Power: Decades trophies - there are 34 bronze, 9 silver, 3 gold and 1 platinum.
Obtain all trophies
Complete a Two-player game in any mode
Complete a Three-player game in any mode
Complete a Four-player game in any mode
Complete a Five-player game in any mode
Complete a Six-player game in any mode
Play five games in any mode
Play fifteen games in any mode
Play thirty games in any mode
Use all of the game's characters
Use a Power Pick twenty times in total
Use a Power Pick on a door choice, play Points Party and then be the only player to get the question wrong in a 3-6 player game
Answer first but be the only player to get a multiple-choice question wrong in a 3-6 player game
Play five Power Plays on one character on the same question in a 4-6 player game
Come from last in the Finale to win a 3-6 player game
Complete all 15 pairs in a 'Missing Link' challenge
Sort all 25 answers correctly in a 'This Or That' challenge
One character has 3+ Freezes applied in one round in a 4-6 player game
Win a game with all characters in any mode
Answer all multiple-choice questions correctly in a Standard Game with all players
One character has 3+ Gloops applied in one round in a 4-6 player game
Place a Bet on a player that answers correctly first, but get the wrong answer yourself in a 3-6 player game
A player Power Picks a door when all other players had agreed on a different door in a 3-6 player game
Everyone Freezes everyone else on a question in a 3-6 player game
When Glooped, remove ALL the Gloop from your answer screen
When Bombled, one player taps two bombles on a single answer screen
When Frozen, remove ALL the Ice from your answer screen
Choose an incorrect answer to a multiple-choice question with only one player in a 3-6 player game when all other players get it right
Choose the same incorrect answer to a multiple-choice question with all players in a 3-6 player game
Choose all four doors, with at least one character on each door, in the door choice screen in a 4-6 player game
Get the correct answer to a Finale question after trying all the wrong ones
All players use their Power Pick in a game
Be the only person to miss out on a Points Party in a 3-6 player game
Clear all 15 questions in a 'Chain Reaction' challenge
Complete all 15 answers in a 'Fill The Blanks' challenge
Clear all 15 questions in an 'Odd One Out' challenge
Clear all 15 questions on a 'Spin To Win' challenge
One character has 3+ Zippers applied in one round in a 4-6 player game
One character has 3+ Disco Infernos applied in one round in a 4-6 player game
One character has 3+ Lockdowns applied in one round in a 4-6 player game
One character has 3+ Bugs applied in one round in a 4-6 player game
One player uses 50/50 twice in a game
Three different decades are picked in one game
The same decade is picked three times in one game
One character has 3+ Bombles applied in one round in a 4-6 player game
One character has 3+ Letter Scatters applied in one round in a 4-6 player game
A player uses a Points Doubler on a question and achieves the highest score (answers correctly first)