Jackal

An Iron Code Burst 1 tank, close to top-tier in the Arena thanks to even damage distribution and Burst Gauge contribution.
She is rarely included in main Story, Raid, or boss lineups.

At battle start, Jumpin' Jackal Flash2 splits damage taken between her and the 2 highest-ATK allies and raises DEF. Every 10 hits taken, Happy Jackal1 applies Damage Taken increase and ATK reduction to the 1 enemy with the highest Max HP.

Crazy JackalB raises all allies' Burst Skill damage and DEF for "1 enemy" target Bursts. Hits received through damage distribution also count toward Happy Jackal1's hit count, so Burst Gauge fills quickly in the Arena.

Set P1 and back-row positions so the top 2 ATK allies and Jackal share hits.
Charge-fire her clip Rocket Launcher to fill the gauge.
Outside the Arena she has little value, so auto alone is fine.

Scarlet nuke variants with Pepper or Drake are also used. For PvE main Burst 1, her role overlaps with Liter and Volume.

In the Arena, go Quantum Cube (gauge), Vigor Cube (survival), then Tempering Cube (damage mitigation).

For an Arena Rocket Launcher, Charge Speed lines are very noticeable. Remaining lines go to DEF, Iron Code damage, and other PvP survival or CP boosts.

If you use her only in the Arena, raise Jumpin' Jackal Flash2 and Crazy JackalB together. For PvE only, she is low investment priority.

Her core is Arena damage distribution, Burst Gauge, Scarlet and Emma nuke lineups, and defense lineups. She only boosts single-target Bursts, so she is rarely a PvE main.

Jumpin' Jackal Flash2's even damage distribution keeps DPS alive.
Every 10 hits taken, Happy Jackal1 applies a debuff and contributes Burst Gauge.
Enemy Shotgun pellets register as multiple hits, giving her an edge in the Arena Shotgun meta.

Crazy JackalB only boosts Bursts that target 1 enemy, so it does nothing for AoE Bursts.
In PvE, her role overlaps with Burst 1 units like Liter and Volume.
She can be weaker against some counter lineups such as Rosetta.