Here is the full list of all 36 Desperados III achievements.
Complete 5 of the Baron's Challenges.
Earn 90 badges.
Kill 31 hidden Mimimi devs.
Hide 750 bodies.
Kill 200 guards using Cooper's double shot.
Make guards follow Kate for 1,000 meters total.
Kill 75 guards with Bianca.
Snipe 50 guards with McCoy.
Mind control 25 guards with Isabelle.
Defeat Frank.
Kill all 3 golden chickens.
Kill 75 Long Coats.
Take care of DeVitt.
Kill DeVitt.
Jump from a tower into a cart of hay.
Interrupt an important healing procedure.
Kill 6 guards at once using only a single skill.
Kill 1,000 guards.
Meet Frank on a boat.
Find Wayne.
Kill 10 small animals in one mission.
Kill 15 of the hidden Mimimi devs.
Enjoy some cupcakes during a picnic.
Execute a plan with all five characters.
Find a patient for the dentist.
Return the money to the bank.
Hide 250 bodies.
Make someone follow your footprints for 25 meters.
Blow up a bridge.
Kill 500 guards.
Knock out your father.
Kill 50 guards using the environment.
In the first part of the mission, burn 5 guards at once with oil traps.
Finish a mission on "Desperado" difficulty.
Decide the outcome of a duel.
Kill 5 guards at once with dynamite.