SugarHas Favorite Item

With her Favorite Item, she became a core buffer and DPS for Water and Iron Shotgun squads.
She grants Water and Iron Shotgun allies a big Elemental Advantage Attack Damage increase and also gets Elemental Advantage damage against Fire enemies herself, so she fits Shotgun squads for both Fire boss fights (Water has the advantage) and Electric boss fights (Iron has the advantage).
In Water-weak Solo Raid Shotgun squads she appeared in every top record, but her buffs are limited to Shotguns of two elements, so she has little use outside Shotgun squads.

While her cover is intact, attack damage increase applies constantly, and each time her cover is hit, Critical Damage and Reload Speed rise and cover HP is restored. From battle start, Elemental Advantage damage also applies to her against Fire enemies.

When Full Burst starts, her Critical Rate and ATK rise and Max Ammo for all Shotgun-wielding allies increases for 15 seconds, and Water and Iron Shotgun allies among them also gain increased Elemental Advantage Attack Damage. When Sugar uses her Burst, her attack speed, Hit Rate, and ATK rise and Water and Iron Shotgun allies gain increased Elemental Advantage Attack Damage once more, keeping two Elemental Advantage buffs active side by side during Full Burst.

Basically leave her on auto.
Sugar's Burst grants Shotgun allies in the same squad increased Elemental Advantage Attack Damage, so set the order so Sugar's Burst is not skipped at Burst stage 3.

In Iron Shotgun squads, she is used with Tove, Arcana: Fortune Mate, Soda: Twinkling Bunny, and Drake (Favorite Item).

Supplement ammo with Bastion Cube, and if your Resilience Cube level is higher, use Resilience Cube.

Her Burst attack speed increase burns ammo fast, so secure Max Ammo, and add Hit Rate only as much as her Burst's Increased Hit Rate leaves you short.

The Water and Iron Shotgun ally Elemental Advantage buff and ammo increase are on S2 and Burst, so raise those two first. S1 covers the cover-survival attack damage increase and Elemental Advantage against Fire enemies, so set it last.

Used in Shotgun squads for Fire boss fights (Water has the advantage) and Electric boss fights (Iron has the advantage).

She grants Water and Iron Shotgun allies a big Elemental Advantage Attack Damage increase through Full Burst and her own Burst.
She is Iron herself, but Elemental Advantage damage also applies to her against Fire enemies, so she fits Raids of both elements.
She greatly increases Max Ammo for all Shotgun allies for 15 seconds.

Her Elemental Advantage buff targets only Water and Iron Shotguns, so it does little in other squads.
When her cover breaks, her constant attack damage increase turns off.
She needs her Favorite Item fully upgraded to perform.