TotK update:
If you have plenty of Keese eyes, multi-shot bows, and anti-environment outfits at least up to level 2, Gleeoks are easy.
They just fucking sit there and let you shoot at them. Even in the last bit where they fly in the air, you can still get up to them where you can shoot them with arrows and hope they take enough fall damage to where they die.
Kinda disappointing that they don't really do anything special. Even when they fly up and rain down death from the sky, they still just sit there.
Silver and White Lynels seem to be the only menacing enemies in the game. Flux Contruct IIIs can be annoying if you get stuck when them in the cube mode because they shift their crit spot around so quickly and often, but Riju's ability almost makes that a non-factor, too.
Kinda wish they incorporated the Aerocuda flight patterns into Gleeok movement. Would love to try to dodge their flybyes. The way you have to try to get up to their level on their final stage is kinda meh. The Frost Gleeok is the most inventive one, but its still a pain, and you kinda need a piece of the Froggie suit.