The best team in my opinion (this goes for the gorilla boss as well) is 15 rexes, 2 yutys, and 3 daeodons. If you can't get your hands on all 15 rexes, megatheriums work just as well bc of their buff when they kill bugs. When they kill a spider minion, they get a damadge buff, helping them defeat the broodmother. Do not use them for the gorilla boss, just use allos instead.

More Broodmother Lysrix Encountering Tips