Todomomo

Todo: fire bender or water bender
Momo: earth bender

Kirimina

Kiri: earth bender
Mina: fire or earth bender

Miruhawks

Rumi: earth bender
Hawks: Airbender

Iidamei

Iida: air bender
Mei: non bender

Kamijirou

Denki: fire bender
Jirou: earth bender

Dabi x Toga

Both are fire benders

Nejitama

Air bender Nejire and Earth bender Tam tam

Mt.Kamui

Both are earth benders

Ryushot

Ryuko is the fucking avatar- jk she's an air bender.
Shinya: air bender

HitoRei

Reiko: airbending
Hitoshi: water bender

Tetsukendou

Both are earth benders

SetSero

Water bender Sero, Earth bender Setsuna

Shintati

Earth bender or Air bender Shindou, and air bending Tatami

Fatjoke

Water bending Emi
Boomerang bending Taishiro