Here is the full list of all 35 Smashing Spirits: Brazil's First Boxer achievements.
Unleash the 4th overload level.
Finish cave's level in less than 17 minutes (killing all enemies on hard).
Finish cave's level in less than 6 minutes. (on hard)
Kill all enemies on cave level. (on hard)
Complete all levels on hard, including the bosses and get all secrets.
Finish river's 2nd level in less than 4 minutes. (on hard)
Finish river's 1st level in less than 4 minutes. (on hard)
Finish river's 1st level in less than 9 minutes (killing all enemies on hard).
Finish forest's 1st level in less than 4 minutes. (on hard)
Finish forest's 2nd level in less than 4 minutes. (on hard)
Finish forest's 1st level in less than 7 minutes (killing all enemies on hard).
Finish river's 2nd level in less than 10 minutes (killing all enemies).
Rescue all monkeys on 3 levels.
Kill all enemies on 3 levels. (on hard)
Finish forest's 2nd level in less than 7 minutes (killing all enemies on hard).
Catch all hearts on 3 levels.
Complete all levels, including the bosses.
Complete all levels on hard, including the bosses.
Defeat cave 2nd boss on hard.
Defeat cave's 2nd boss in less than 90 seconds (on hard).
Defeat cave 1st boss on hard.
Defeat cave's 1st boss in less than 3 minutes (on hard).
Do 3 full combos in a row.
Finish cave's level on hard.
Defeat river's boss on hard.
Defeat river's boss in less than 2 minutes (on hard).
Finish river 2nd level on hard.
Finish river 1st level on hard.
Defeat forest's boss on hard.
Defeat forest's boss in less than 2 minutes (on hard).
Do a 30 hits combo.
Do a 20 hits combo.
Finish forest 2nd level on hard.
Finish forest 1st level on hard.
Do a 8 hits combo.