For this I used the Easy Mode Shield, Peak Opener Assault Rifle, Mouth Wash Relic, and Electric Chair Grenade. I farmed Haderax for the Easy Mode shield and Peak Opener assault rifle. Got the Mouth Wash Relic from the main quest line in the DLC and the Electric Chair Grenade from farming the boss Uranus.
If you don't want to farm for four weapons and have a friend you can duplicate the weapon by saving your game dropping it on the ground then hitting the home button and closing the application and joining back on your friend and repeating til you have four of whatever effervescent weapon you have.
Anyone who doesn't really feel like farming feel free to message me within the next week or so of me posting this and I'll duplicate my gear with you for the trophy I don't mind at all.