Here the Z-Sigil won't affect the set or weapon used.
The best weapon for this fight is the Leo Aquasword "Shine". Since the Evo only has mediem length a length up sigil will be very helpful.
Sigil 1: [ SnS Up 15 | Beam Slash | Length ]
Sigil 2: [ Element 15 | Element 15 | Element 15 ]
Sigil 3: [ Element 15 | Element 15 | Element 15 ] or [ Element 15 | Duration 12 | Wait Time 17 ]
I still need to figure out how good Stylish Assault Up is in this fight, but for now I don't think it outperforms Ice Age or Ele attack up.
Take the All Elemental Drug right away after spawning. After both PD's move to Disu's hindlegs and take both the SW Potion and the Water Attack Fruit.
In the Phase Transition to the last phase go behind him and use your Power Crystals a whetstone and an Affinity Drink.
In this fight you'll have to fish for i-frames as much as possible. Learning his hitboxes precisely is therefore really important. Also his ice that he puts on the ground can be i-framed when it disappears but the timing is not easy.
Here are some clips of moves that are important to get the I-frames from:
When you see him do this animation with its head in phase 3, walk away and run back in through the flames.
When he goes up in the air for this attack, move towards him and stay within the ice on the ground. You can hit him with a beamslash when he comes around and be sure to get the i-frame when the ice explodes on the ground when he crushes it.