Here is the full list of all 17 Square x Square achievements.
Be winner playing as Red Square
Be winner playing as Blue Square
Be winner playing as Yellow Square
Be winner playing as Pink Square
Play 50 matches in a row
Win a "bo5" without lose
Start a match with 4 players
Time reaches 0
Win a game without attacking
You have 1/10000 chance to win this when the match starts
Start a match on team mode
Win the match on the last seccond
Both players with 1 life
Play 3 matches in a row using boomerang
All three players with 1 life
All four players with 1 life
Win the match before 100 sec