I think you're exagerating a little bit, anyway i mostly agree with Boolerex for the most of think he said.
I just give you my suggest for some class i already mastered most of the variants.
Imp. Imp need health to be 50 again. Anyway buffing Impkata damage will mess the game again, so my suggest is just to give this move some utility rather than damage, i suggested something in my topic.. like, when you get a kill you gain a little buff bonus.. decent at least
PeaShooter. I nearly mastered with all his variants besides Commando at elite, and i have to say the only one underpowered is Commando, and Fire one with no really unique pick potential, if i want harass potential i pick toxic or electro, the fire blast radius is too little to abuse it for harassing people behind walls, and the direct damage is pretty low, fire is useful though but need time to stack, so even for close combat fights i prefer Regular PeaShooter or Electro.
The only little slighly adjust they could get: Agent Pea less screen shaking so people can actually take more headshots if they're accurate, and Electro Pea slighly projectile speed after the bullet reaches 15-20 metres. Besides that PeaShooter is one of my favorite class together with Citron. Easy to use, rewarding when mastered and pretty strong and balanced.
Kernel Corn is fine for the most, yes, he has bad bullet dispersion, accuracy and damage drop-off, so you can't snipe, that's why they give him 25health more. He's bad character? No. Just very hard to play, The most reason people find him besides BBQ very struggling to play is maybe the actual meta rather than the character itself. I could be wrong, we will see it next patch anyway.
For the Cactus, i ddnt play him a lot because i find him pretty useless to be honest... what i think?
Cactus isn't properly garbage, all his variations besides Camo are fine for the most, Cactus problem is kit itself. All his kit rely on camping only and is very less versatile for many reasons, the first reason is herbaul assault, and the second reason is the new game map design. Mines and Wallnut should have some replacement ability for when you want to play in a different way.