Here is the full list of all 19 Cold Iron trophies - there are 3 bronze, 7 silver, 8 gold and 1 platinum.
Find a creative way to overcome Riverboat Diaz.
Collect every silver (or golden) statue.
Defeat The Behemoth with an A rank or better.
Defeat The Tempest with an A rank or better.
Complete the game from start to finish without dying.
Destroy every watermelon in three bonus levels.
Discover the secret chicken in three worlds.
Defeat Will O' Wisp with an A rank or better.
Defeat Riverboat Diaz with an A rank or better.
Win a round in under 0.2 seconds.
Defeat Cold Iron with an A rank or better.
Defeat The Gunsmith with an A rank or better.
Defeat A.U. 117 with an A rank or better.
Defeat Iris with an A rank or better.
Defeat Nowhere Man with an A rank or better.
Defeat Black Jack with an A rank or better.
Defeat Whiskey Sweet with an A rank or better.
Collect all other trophies.
Collect every golden statue.