Well, Earth Main is marked as BloodLimit user... so everyone got at least 1 type of these attributes

Edit:
Earth: Blood Limit
Wind: Senjutsu
Water: Senjutsu, Swordsman
Lightning: Swordsman, Anbu
Fire: Blood Limit, Secret Jutsu

Would be good, if all mains got "allied forces" tag. So Kurama Naruto can make them immune xD
Otherwise I would give Earth main Senjutsu and Wind Main ... maybe Secret Jutsu...