Here is the full list of all 24 Tunche: Arena achievements.
Clear a Wave without getting hit.
Choose a reward in Horde mode.
Buy a skill in Endless mode.
Defeat Boutu in Horde mode.
Defeat one enemy of each type.
Complete a Wave in Endless mode.
Access any of the Leaderboards.
Defeat Boutu in Horde mode without being damaged.
Defeat 200 frogs in total.
Defeat 75 monkeys in total.
Defeat 30 trunks in total.
Defeat 50 peccaries in total.
Defeat 10 giant frogs in total.
Reach Wave 50 in Endless mode.
Get a total of 50 S, SS or SSS kills in Endless mode.
Air juggle the frog plushie 5 times.
Beat Horde mode without having chosen any reward.
Beat Horde mode without having spent XP on the Skill Tree.
Reach S combo style.
Reach SS combo style.
Reach SSS combo style.
Use all the skills.
Annoy the Skill Tree guy