Here is the full list of all 34 3on3 FreeStyle: Rebound achievements.
Collect every trophy in 3on3 FreeStyle:Rebound
Win 50 Matches - "1vs1 Mode only"
Use Substitution 50 times
Win 300 Matches - "3vs3 Mode only"
Lose 50 Matches
Get 1000 Assists total in any game mode
MVP 200 times - "3vs3 Mode only"
Score 3,000 points total in any game mode
Get 500 Dunks total in any game mode
Get a winning Buzzer Beater - "3vs3 Mode only"
Score 300 3PT shots total in any game mode
Get 100 Steals total in any game mode
Win 10 Matches - "1vs1 Mode only"
Reach Level 20
Get 500 Loose Balls total in any game mode
Win 100 Matches - "3vs3 Mode only"
Score 1,000 points total in any game mode
Play 150 Matches total in any game mode
Reach Grade 5 with any character
Get 300 Blocks total in any game mode
MVP 50 times - "3vs3 Mode only"
Get 500 Rebound total in any game mode
Finish a Match with JOEY
Reach Level 10
Play a Match by making team lineup with two users - "3vs3 Mode only"
Play 20 Matches total in any game mode
10 Winning Streak - "3vs3 Mode only"
Win 10 Matches - "3vs3 Mode only"
7 Winning Streak - "3vs3 Mode only"
Reach Level 5
3 Winning Streak - "3vs3 Mode only"
Unlock the sixth character (Have Six Characters)
MVP for the first time - "3vs3 Mode only"
Get any item at the shop for the first time