EVERYONE IS AN OMEGA OMEGABASEONE OMEGA2BLE GYUVIN IS THE ONLY ALPHA RAAAAHHHH
ok but seriously i would say
hanbin - omega
jiwoong - omega (bitched alpha. i am VERY specific about my jiwoong bitched alpha headcanon)
hao - omega
matthew - beta (could also be omega)
taerae - omega
seungeon - beta/omega (seungeon is a little tricky cause i think he could be both)
ricky - omega (but i could see him as an alpha too)
gyuvin - alpha/beta (same as seungeon, he could be both for me)
gunwook - alpha (i could also see him as an omega too tho)
yujin - alpha

honestly a lot of them could be more than one, it's not really exclusive for me lol. but my fav headcanon is lowkey 'everyone is an omega except gyuvin' ngl