I don’t go full mono often. I usually go 3 - 2 or 4 -1 cuz I’m still lacking some good 4* and 5* heroes.
They’re not the best but these are my mono teams:
Blue: Kiril, Frida, Grimm, Boril, Sonya. I agree with what was written in other comments. Firing Frida first then Grimm does more damage.
Green: Jack O’Hare +11, Jack, Caedmon, Gadeirus, Skittleskull. Pretty succesful team at monthly events. I will swap slow 4* for fast ones someday to be in top 10.
Red: BT, Anzogh, Colen, Scarlett, Kelile. Not so good at raids with bad boards.
Purple: Kunchen, Rigard, Tibs, Proteus, Balthazar+20. A 3* in my purple mono… I need to max Sabina but, too many healers in my team already.
Yellow. Chao, Hu Tao 3/70, Wu Kong, Bane+11 and Danzaburo 4/10. Another 3*. Yellow is my worst team.