Jessie is amazing in Big Game when she is the Big Brawler because she can use her Super to defend herself which also has 20% more health and damage. Her damage and reload speed increase, which along with her bouncing shots and turret make her a very decent Big Brawler in this mode.
In Heist, Jessie's turret can be placed in front of their safe to help defend against enemies by shielding the safe and by dealing damage. Likewise, it can also be used offensively against the enemy safe with the help of her Recoil Spring Gadget to multiply the turrets damage output.
Her Energize Star Power helps keep the turret survive for longer and extend Jessie's range by bouncing her attacks. Meanwhile, her Shocky Star Power will allow Jessie's turret's attacks to bounce off and potentially hit more enemies, who could either be defenders on the enemy side or attackers on your safe.
Be wary of Penny when placing her turret to defend, as otherwise she may be able to use the turret to potentially triple her damage onto the safe.
Recommended Build
Jessie's Spark Plug Gadget is incredibly useful for taking down enemies. It can hit enemies through walls in a radius around the turret. After enemies are slowed down, Jessie can attack the enemy easily, and the turret can hit all shots while the enemy is slowed. Jessie can also use it to defend from heavyweights and assassins.
Jessie's Recoil Spring Gadget, although capable of providing a lot of value, only excels when taking out stationary targets, enemy turrets, or non-dodging spawnables. It works best with her Shocky Star Power, forcing enemies to take damage as they attempt to defend.
When using Jessie's Energize Star power, place her turret near an important chokepoint on the map and keep shooting at the turret to heal it while enemies are near it. This will continuously heal her turret while it deals damage, and her regular attacks can also deal damage to the enemies too.
Strategies
Turret placement is one of the most important skills with Jessie. When facing short-ranged Brawlers, place it out in the open so that they are forced to take attacks from it as they attempt to destroy it. When facing long-ranged Brawlers, place it next to their walls, but on her team's side of the wall so they have to walk around the wall to attack it and take damage. When facing throwers, throw it over the wall that they are hiding behind to do some damage to them and force them to use their attacks on the turret.
Jessie's turret deals small but noticeable damage that racks up quickly. Unfortunately, it can be easily avoided by running perpendicular along its attack direction. Prevent enemies from dodging effectively by placing the turret in a place where it can cover a linear area.
The bounce mechanic of Jessie's attack can quickly cripple entire teams. Lock down choke-points or linear sections of the map to punish grouped up enemies by dealing considerable damage to them and rapidly charging your Super and Hypercharge.
Other
After hitting a target, Jessie's attack always bounces towards the nearest enemy that hasn't already been hit. This can be used to determine enemy positions, even if they are out of range or hiding in bushes, or invisible such as Leon or Sandy.
Jessie's turret can deal considerable damage if ignored, making it an excellent way to distract enemies if they attempt to destroy it. By the time they do destroy it, you are likely to have a fully or mostly charged Super that is ready to be used whenever you wish.
While in a bush, Jessie's turret is invisible to enemies unless they are also in the bush and right next to it. Enemies right next to it in a bush are so visible by Jessie and her teammates. However, just like a Brawler, the turret will become visible while attacking or taking damage.
Jessie can charge her Super very quickly. 6 hits (or 2 perfect shots hitting 3 enemies by bouncing) is enough to charge her Super without any pre-existing charge.
Changelog
20/06/17 The health decay mechanic was removed from Jessie's Super.
27/06/17 Jessie's main attack damage was decreased to 140 (from 160).
11/08/17 Jessie's Super recharge rate was decreased by 12.5%.
16/08/17 Jessie's main attack damage was increased to 160 (from 140). Scrappy's reload time was decreased to 0.25 seconds (from 0.35). Scrappy's projectile speed was increased by 33%.
04/09/17 Scrappy's reload time was increased to 0.30 seconds (from 0.25).
07/12/17 Jessie's main attack's damage was increased to 720 (from 640) per bounce. Jessie's Energize Star Power was added. The health and damage statistics of all Brawlers were multiplied by 4.
16/01/18 Jessie's health was increased to 3200 (from 2800). Her Energize Star Power healing was increased to 800 (from 600).
21/03/18 Jessie's main attack projectile size was increased. Every Brawler's movement speed was increased by 70 points, increasing Jessie's movement speed to 720 (from 650). All Brawlers' projectile speeds are increased by 9%.
09/04/18 Jessie's main attack damage was increased to 780 (from 720) per bounce.
21/05/18 Jessie and her turret were remodeled.
19/06/18 The Summer and Dragon Knight Jessie skins were released.
31/08/18 Jessie's main attack damage was increased to 820 (from 780) per bounce.
05/12/18 Jessie's reload time was decreased to 1.8 seconds (from 2).
29/01/19 Jessie's main attack projectile was re-textured.
07/08/19 Jessie's Shocky Star Power was added.
18/09/19 Summer Jessie's main attack visual effects were reworked.
09/10/19 Jessie's main attack damage was increased to 840 (from 820) per bounce. Scrappy's damage was increased to 260 (from 240) per shot.
23/10/19 Dragon Knight Jessie's projectile was re-textured, and the Shadow Knight Jessie skin was added.
05/12/19 Jessie's main attack projectile speed was increased by 10%. Scrappy's health was increased to 3000 (from 2800).
17/03/20 Jessie's Spark Plug Gadget was added.
29/04/20 The Tanuki Jessie skin was added.
09/06/20 The Red Dragon Jessie skin became available to every user until 30/7/20. It was featured to celebrate the launch of Brawl Stars in China.
12/08/20 Jessie's Recoil Spring Gadget was added.
10/09/20 Jessie's Super recharge rate was increased slightly. Her Super charge rate was decreased slightly. Jessie, Red Dragon Jessie, Summer Jessie, Dragon Knight Jessie, and Tanuki Jessie received facial animations.
15/12/20 Jessie's main attack damage was increased to 920 (from 840) per bounce. Scrappy's health was increased to 3200 (from 3000). Jessie's Energize Star Power healing was increased to 896 (from 800). Jessie's True Silver and True Gold skins were added.
27/01/21 Jessie's main attack damage was increased to 1120 (from 920) per bounce. Each bounce from her main attack now deals 25% less damage. Super charge rate was unaffected. Shadow Knight Jessie received facial animations.
08/02/21 Jessie's main attack damage was decreased to 1060 (from 1120) per bounce.
15/03/21 Jessie's health was decreased to 3000 (from 3200).
19/05/21 Scrappy's health was decreased to 3000 (from 3200).
27/10/21 Jessie and her turret were remodeled, along with her True Silver and True Gold skins. Jessie's class was changed to Damage Dealer (from Fighter).
26/11/21 The Cat Burglar Jessie skin can be obtained by gaining 1000 points at [https://event.brawlstars.com event.brawlstars.com] during the World Finals 2021.
16/12/21 Jessie's facial animations were slightly reworked.
29/06/22 Shadow Knight Jessie's main attack visual effects were slightly reworked.
12/12/22 Scrappy's health was increased to 3300 (from 3000). Jessie's rarity was changed to Super Rare (from Common).
28/02/23 Jessie's class was changed to Controller (from Damage Dealer). Summer Jessie, Tanuki Jessie, and their turrets were remodeled.
25/04/23 Shadow Knight Jessie now costs 49 Gems (from 10000 Star Points). Red Dragon, Dragon Knight, Shadow Knight Jessie, and their turrets were remodeled.
05/09/23 All Brawlers' health and damage were increased from 5% to 10% with each Power Level.
24/10/23 Jessie's Energize Star Power healing was increased to 954 (from 896) and now scales with Power Levels. Jessie's Scrappy 2.0 Hypercharge was added. Shadow Knight Jessie's main attack and Super visual effects were reworked. Jessie's flavor text was changed from "Jessie's Shock Rifle shoots energy orbs that bounce between enemies. Her Super deploys a cute but deadly gun turret!" to "Jessie is a prodigy who builds guns and gadgets from parts she finds in the junkyard. Maybe one day her mother Pam will see she can fend for herself!"
14/02/24 The Doll Jessie skin was added. It was featured as a My Brawlentine skin.
27/02/24 Jessie's Scrappy 2.0 Hypercharge multiplier was increased to 60% (from 40%). Jessie's Scrappy 2.0 Hypercharge damage boost was increased to 25% (from 20%). Jessie's Scrappy 2.0 Hypercharge speed boost was decreased to 26% (from 30%). Jessie's Scrappy 2.0 Hypercharge shield boost was decreased to 5% (from 20%). All Brawlers' Hypercharges duration can no longer be extended.
11/04/24 The Skadi Jessie skin was added. It was featured as a Northern Saga skin.