Villain Team entry...LETHAL LEGION

[Monolith]

While the Masters of Evil are more famous, the Lethal Legion have also harried the Avengers since their early days. Usually the minions of Count Nefaria or the Grim Reaper, the Legion tends to be in it for the money rather than personal vengeance or world domination. They maintained a colorful roster over the years, starring Avengers villains from Ultron to Whirlwind, and inspiring many imitation groups as well.

https://mightyavengers.net/groups/lethal-legion

[EvilMonkeyPope]

What about Mutant-X's Lethal Legion?
http://www.marvunapp.com/Appendix2/lethallegionmx.htm

[Monolith]

This entry only covered Earth-616 teams who used the name.

[Holland Oates]

My favorite is the grouping of Count Nefaria, Grey Gargoyle, Whirlwind, and Living Laser. But I think it would be more appropriate to call them the Nefarious Four (since legion implies a lot more characters and because their powers mostly complement the FantasticFour).