Here is the full list of all 12 Watchmen: The End is Nigh Part 2 achievements worth 200 gamerscore.
Complete the game as Nite Owl.
Complete the game as Rorschach.
Complete the game in Co-operative mode.
Perform all 8 Nite Owl combos within 60 seconds.
Perform all 8 Rorschach combos within 60 seconds.
Eliminate an enemy that your partner has knocked down or thrown in your direction.
Take down 10 enemies in a row finishing off each of them before doing damage to anybody else.
Hit 14 enemies with a single electrify armor blast.
Sustain a single rage mode for 60 seconds.
Hit at least 4 different enemies while building up a combo.
String a single uninterrupted combo that's at least 10 hits long.
Complete Chapter III without hitting any ladies before they hit you.