Viper / Madame Hydra ?





Doctor Minerva ?
(who is a main foe of nearly anybody who uses Marvel as a name anyway ...)
https://comicvine.gamespot.com/dr-minerva/4005-26673/

Probably, there is also Doc.X ...
https://comicvine.gamespot.com/doc-x/4005-137617/





Yes, Titania is the only famous villain in her rogues gallery who could be considered one of her personal archfoes.

In the first She-Hulk series, Nicholas Trask, Beverly Cross and Doc were three attempts to give She-Hulk her own archfoes.
http://www.marvunapp.com/Appendix/trasknic.htm
http://www.marvunapp.com/Appendix/crossbev.htm
http://www.marvunapp.com/Appendix/docshulk.htm

Ultima & her father, the Word, might have become main foes but they only battled her on one occasion.
http://www.marvunapp.com/Appendix/ultima.htm
http://www.marvunapp.com/Appendix/wordsheh.htm



... but, anyway, all these obscure characters are totally forgotten, nowadays.




This question is easier : Spider-Man, Simon Stroud, Martine Bancroft and Vic Slaughter.
http://www.marvunapp.com/Appendix6/stroudsimonmorb.htm
http://www.marvunapp.com/Appendix6/bancroftmartinemorb.htm
http://www.marvunapp.com/Appendix4/slaughtervicmorb.htm

In a way, probably more than any other Marvel character, Morbius is his own worst enemy.




See the link below for the detailed information :
http://www.comicboards.com/php/show.php?rpy=mub-2017121214350767
Carol Danvers has a lot of archfoes : Supreme Intelligence, Brood Queen, Deathbird, Grace Valentine, Skrulls (especially War-Skrulls) ...




Unfortunately, I think that Marvel never cared enough about Monica (and that's a shame) to give her a proper rogues gallery. The villains appearing in the Nextwave comic book might be regarded as her main foes.
http://www.comicboards.com/php/show.php?rpy=avengers-2017101911483253
https://comicvine.gamespot.com/nextwave/4060-40478/enemies/




http://www.comicboards.com/php/show.php?rpy=mub-2017101309390475
The Sphinx, Condor, Diamondhead




I honestly don't know ...
https://comicvine.gamespot.com/sam-alexander/4005-82858/enemies/

Probably, Titus ?
https://comicvine.gamespot.com/titus/4005-87738/




Aaron Davis ?




I had to look for her list of enemies to guess what could be the answer.
https://comicvine.gamespot.com/tigra/4005-21188/enemies/

Tabur and Kraven the Hunter might be her main foes.
http://www.marvunapp.com/Appendix2/taburtigra.htm




Buzz Baxter (Mad Dog)
http://www.marvunapp.com/Appendix3/maddogbaxter.htm
When she was dating Daimon Hellstrom, Satan (Marduk Kurios) was one of her main foes.
http://www.marvunapp.com/Appendix/mardukkurios.htm