Gotham Knights

Ok, so to be even able to attempt this you must have completed all the Villans case files in your game.

Harley Quinn, Clay face, Mr. Freeze and the main game must also be completed as well for Talia al Ghul

one all those are done for the original cases you can go under the staircase in the belfry and launch all of the specific boss battles needed for the achievements.

they all have various power levels but me and my buddy didn't really struggle on any even though we were lower power by a bit.

Mr. Freeze showdown (9,900 POW)

tips: Avoid all his projectiles as he is pretty easy to beat

Mecha Freeze showdown (15,300 POW)

tips: His legs will collapse, and you can do extra damage as long as you avoid projectiles, you'll be fine

Harley Quinn showdown (12,400 POW)

tips: We bombarded her with stuns and excessive damage as she focused on the other

Clay face showdown (18,400 POW)

tips: Just chip away with projectiles as his health is massive.

Talia Showdown (21,912 POW)

Tip: She has 2 phases and in both she will try to use the pit to heal, Stagger or stun her with ability and she is cake. She also steals your meter with hits in phase 2 so be careful

I was red hood, and my partner was nightwing, and I did majority of the damage just aiming and shooting critical hits.

we also ran our showdowns in NEW GAME+ so I have zero clue if you can do it in the first playthrough.

Please let me know of any workarounds or tips I missed, Thanks