Rocket shield, spring, fire + pinecone... Any way to fly. Let loose guided arrows or gibdo arrows if close enough. Two handed charge attack while down. Final phase depends on the gleeok. Lightning immunity helps on some of them.
I fuse my arrows with eyeballs to stun each head, use a charge attack with my strongest 2-hand weapon, and dodge the other attacks. Always use 3x attack up, wear the appropriate elemental gear to nullify attacks, use the sages for extra attacks/distractions. They can be pretty easy if you pay attention to where they are and recognize their attack patterns. Like when their health gets low and they fly up high to unleash a massive attack. That takes time so you need to get up there and take out their heads before it's too late or take cover.
Edit: Also consider fusing the stone slabs. Two long ones 90 deg to each other and a corner one to make a roof that's high enough to just Ascend through. You can hide behind it to sneak up to them, use it to get bullet time, and use it for cover.
There are auto builds without Zonai parts at all, like particularly an instant scaffold that is perfect for fighting gleeoks. I want to say that the simplest one is 9 or 12 zonaite.
That said, I tried using it once but my timing was off and it fell down so I did the entire fight from the ground using a 3x lynel bow with keese eyeballs fused to the arrows. It wasn’t too bad at all, as it was a frost gleeok and my snowquill armor is level 3, making its attacks largely ineffective
You can use an octo baloon shield instead of spending a rocket.
You can parry the lasers but since they are continuous, you end up getting hit after the parry and you don't reflect them back.
The best damage combo once it's down is to be at 1 heart or less with a molduga jaw knight's claymore, Evil Spirit armor (Phantom Ganon) or Radiant armor (glow in the dark skeleton luchador), and attack lvl 3 food. This allows you to kill it in 1 cycle. I think the base damage of that sword is 128 displayed, the armor multiplies by 1.8 (cause the jaw is considered a bone) and the attack buff by another 1.5. This assumes the sword has the attack + modifier and is pristine.