To start, I'm a Hunter who is currently 58th level.
MM 44
ZMM 56 (Hadn't tried earlier then that)
JrRog Haven't tried yet
CrRog Haven't tried yet
Mushmom - 45ish
Zombie Mushmom - 50-52ish
Jr. Balrog - 65
Can't hit Crimson yet.:(
MM - 51,I was scared, most of my friends did it earlier than that, and I thought bosses would be harder (more than just weirdo jumping)
ZMM - 73, that's when it came out and I found an empty channel
Jr. Rog - 73, I was already at zmm and I thought "hey, why not get 2 bosses ?"
Crog - 90, low hp + weak close range attack = I need a dk, I just got HB from a 6x dk, then he ran inside and I pwned it.
Hmmm for me, I didn't really bother with MM and ZMM until later levels, so I won't list those, but I solo'd Jrog and Crog at LV70 when I got ME lol
Hmm, I am a Cleric/Priest level 100 atm.
I still haven't killed a MM on this char but I'm guessing I could have done it at around level 45.
ZMM at 47 (it took me 5 minutes literally).
JRog at level 67, which was not too bad.
Fake papulatus at 73.
BMM at 92.
C.Rogs at 100. (could have done it earlier)
And yeah it depends on class.
???