Here is the full list of all 18 Riddled Corpses EX trophies - there are 5 bronze, 2 silver, 10 gold and 1 platinum.
Unlock all trophies in Riddled Corpses EX
Complete stage 1 in story mode
Complete stage 2 in story mode
Complete stage 3 in story mode
Complete stage 4 in story mode
Complete stage 5 in story mode
Complete stage 6 in story mode
Complete arcade mode
Survive through 5 waves in survival mode
Unlock the MK 1000
Unlock the turrets
Unlock all the characters
Upgrade at least 4 characters to max level
Burn 100 enemies during the same run
Electrify 30 enemies during the same run
Complete stage 4 in story mode without using any special item
Die in any mode
Get at least one of each collectible item