Here is the full list of all 23 Mega Coin Squad achievements.
Complete 1000 rounds in multiplayer
Bank a total of 100,000 coins in single player
Complete the single player game with Steph
Complete the single player game with Data
Complete the single player game with Mouth
Complete the single player game with Chunk
Complete the single player game without using any continues or retries
Complete the single player game and collect all available gems
Bank a total of 50,000 coins in single player
Complete the single player game with Mike
Complete the single player game within 30 mins
Collect the Mega Coin from Lava Land in single player
Bank 1000 coins in a single bank in single player
Bank a total of 10,000 coins in single player
Complete 10 rounds in multiplayer
Collect the Mega Coin from Snow City in single player
Complete a single player level in under 30 seconds
Collect the Mega Coin from Desert Plains in single player
Earn all available gems in a single player world
Die without collecting a single coin in single player
Collect the Mega Coin from Green Valley in single player
Earn 3 gems in a single player level
Complete a single player level in under 60 seconds