Here is the full list of all 13 Secret Ponchos trophies - there are 10 bronze, 2 silver and 1 gold.
Achieved "Bandit" reputation with an outlaw
10 match win streak
Came first in Free For All 5 times
No damage taken in 10 1 vs 1 matches
Achieved "Outlaw" reputation with an outlaw
Achieved "Death Bringer" reputation with an outlaw
Ended an outlaw's 10+ winning streak
Reached "Death Bringer" status with 5 outlaws
Defeated an Outlaw in 1 vs 1 Ranked Deathmatch
Defeated a Death Bringer in 1 vs 1 Ranked Deathmatch
Played 50 competitive matches
Won 100 matches
Achieved a win/loss ratio of 2 (Outlaw or Higher)