Check the mod priority guide:
https://docs.google.com/spreadsheets/d/1ty239kyJbBs1sLhTo1JvSWuN0mIJsK1nwVdI6OLLtXo/view?rm=minimalPP-19 MOD has a fairly good upgrade. Meta shifts are sadly not kind to her though, which leads to the simple fact that PP-19 MOD doesn’t really offer anything you need.
Let’s go over the good regardless, because there is good to be found here. Her Skill 2,
Savage Instinct, has her mark the enemies she damages with her grenade. If marked enemies are still alive after a grenade throw, each of her remaining dummy links will throw an additional weaker grenade. This does mean that she is link-dependent for her grenade DPS, which is not desirable on an off tank.
The other part of her skill is based around her MOD3 Special Equipment. If she has it equipped, she’ll check her own HP every 6 seconds against everyone else in her column. If she has the highest HP, she will boost her Damage for 15 seconds; otherwise she’ll boost her Evasion. Note that due to PP-19’s HP being lower than popular main tanks, she can struggle to get the Damage boost. These buffs always stack, so she can get up to a theoretical extra 33% Damage or 33% Evasion this way. On top of this skill, PP-19 gets the usual assortment of buffs. A nice increase to her HP and Damage particularly, as well as a stronger Skill 1 and tiles.
PP-19’s main issue primarily stems from the meta. ARSMG teams in general are losing favour compared to RFHG teams, while offensive tanks are becoming less and less desirable in general. In situations where you want an offensive tank, most would turn to Uzi MOD first, and really that’s mostly all you need. As such, there’s just not much need to do PP-19’s upgrade. Her fans will find an enjoyable upgrade though, she’s still decent and by no means bad at all.
MOD2 is the recommended level.