This is my guide of the Scientist in Plants vs. Zombies: Garden Warfare. To see the guides on Peashooter, Foot Soldier or Cactus, go here, here or here. If I make a mistake, please leave it down in the comments below.
So, the Scientist is the healer of the zombie team and the zombie counterpart of the Sunflower. The Scientist uses the Goo Blaster, or the Zomboss Goo Blaster as it was called in beta, which deals low damage from long ranges and huge damage at short ranges. Unlike the Sunflower, the healer of the plant team, the Scientist does worse at long range but has the benefit of around 70 damage at short range which the Sunflower can only deal up to 10 damage. A Scientist can clear out bunches of plants if in CQC. It used to deal more damage before the Tacah-de-Taco Party DLC, which he can deal up to around 80 damage, but PopCap said "the weapon was stronger than intended". This zombie definitely does not look weak as a Sunflower, oh PvZ logic.
Damage: 11-44 (impact) 22-77 (critical)
Ammo: 5 (6 upgraded)
Now let's go into the variants. Dr. Toxic is the "toxic" version of the Scientist, but deals less damage than the Scientist himself. Also, to make him better, when plants stand near him his aura deals 2 damage per second and this also happens after he shoots his primary weapon at a plant even when not close. So Dr. Toxic can damage plants without lifting a finger! Isn't that neat? Unfortunately he's not a very good variant in my opinion.
Damage: 2 (additional damage) 10-32 (impact/critical)
Ammo: 5 (6 upgraded)
This guy is great for crowd control, especially in Gardens and Graveyards and Gnome Bomb. He can deal up to 60 damage, along with the electric shock, which is cool, but has the same ammo capacity as the default Scientist and Dr. Toxic. I suggest using him, I know most people don't bother to use him, but really, check this guy out. The wiki page says he can deal up to 90 damage, but I haven't experienced this yet.
Damage: 7-30 (impact) 12-60 (critical)
Ammo: 5 (6 upgraded)
Now we go to this guy. One of the baddest of the baddest of the baddest of the baddest of Scientist variants. This guy was HEAVILY nerfed in the Sorrow of the Lawn DLC, with his fire rate and damage, but he's still a beast in the right hands. I'm not saying he's better than Chemist, but still, a powerful character especially when fighting plants in crowds.
Damage: 7-30 (impact) 11-52 (critical) (can rarely deal 60-90 damage)
Ammo: 6 (7 upgraded)
This variant, unlike the other Scientists, isn't mainly used in CQC, but instead fires a rapid-firing Moon Rock Launcher which can be used at any range. The clip has the most ammo out of any other Scientist variant too. I recommend using him if you struggle with most other Scientist variants, but this variant is not great when facing crowds of plants.
Damage: 13-18 (impact) 16-22 (critical)
Ammo: 15 (18 upgraded)
This guy is good. Has it all: Healing, the best damage, and a beast in crowd control. But the only disadvantage is range. What I mean is it can't damage in mid to long range, and can only be effective at short range. Despite all that, it is OP. You unlock this character when leveling up to Scientist Level 10, and you'll be surprised how powerful this character is. I can't believe how powerful this character was before the Tacah-De-Taco DLC, he had slightly more range and more ammo in the clip. I would be okay with less ammo, but the Chemist should've kept that longer range. Still, a very neat character.
Damage: 32 (rooted plants) 40 (common impact/critical) 80 (uncommon to rare impact/critical) 120 (very rare impact/critical)
Ammo: 6 (8 upgraded)
I haven't played with this character a lot, but if you struggle with most other Scientists, I recommend this character. It shares lots of similarities with the Astronaut, has a rapid-fire weapon and lots of ammo in its clip. However, it deals more damage than the Astronaut, but has -3 ammo compared to the Astronaut.
Damage: 12-19 (impact) 17-34 (critical)
Ammo: 12 (15 upgraded)
This guy isn't that great, but he isn't bad either. That buff really made him improve. He's like the Chemist in a way because he can't damage plants at long range.
Ammo: 8 (used to be 6)
Damage: 30 (used to be 25)
Now one of the best Scientists is....wait for it...wait for it......DUN DUN DUN!!
This guy has a lot of ammo in his clip, deals fire damage and plus deals a decent amount of damage. It deals more damage than Dr. Toxic even, and has more ammo. This variant is great. It is also better at long range than most other Scientist besides Archae and Astro.
Damage: 7-17 (impact) 17-42 (critical) 5 (additional damage)
Ammo: 12 (15 upgraded)
Now we go on to the abilities. There are three abilities, with two alternates.
The Warp is great for fast transportation and also warping to plants to deal huge amounts of damage. You have two in stock, which is good. However I don't really recommend this ability as other abilities are better in my opinion. Rating: 7.5/10.
Zombie Heal Station
The Zombie Heal Station is only good for healing teammates, which makes a big difference. However, the Cheetah Heal Station and sometimes Armored Heal Station are more superior than this health station. This ability only lasts for 30 seconds. Rating: 6.5/10.
Sticky Explody Ball
This ball is used for damaging any plants that comes near it. It deals 50 damage if it detonates. This ball can be destroyed by plants, but not much people know that, however it will still explode and damage any nearby plants. You can deploy 2 of these before it cools down. Rating: 8/10.
This ability makes the Scientist invulnerable to damage, as he transforms into a ball of energy. However, the Scientist will go slower in this state unlike the Warp, but it lasts longer. I recommend because you can dodge enemy fire, and plus having a better chance to where you want to heavily damage a plant at. Rating: 9.5/10.
Armored Heal Station
This heal station has lots of health, and plants will never destroy it. However, the drawback is the heal station heals at a slower rate, and lasts for only 20 seconds, but is still a good ability. Rating: 8.5/10.
Mega Heal Bomb
Because how powerful the zombies are already because with the Heal Station alone, I don't need another healing mechanism for the Scientist. If it damaged plants, though, I might consider having it, but since it doesn't, I don't recommend using it. It heals zombies by 50 if in its range. Rating: 7/10.
This is just like the Regular Warp but instead deals 30 damage to plants nearby with also some splash damage. The only drawback is you only have one before cooling down. This ability is still good, but I use Energy Warp most of the time. Rating: 8.75/10.
Cheetah Heal Station
This Heal Station is the most superior, and heals at a fast healing rate, even faster than the normal Heal Station's. The only drawback is it disappears at a disappointing 15 seconds, but I still recommend using it. Rating: 9.75/10.
Sticky Cheetah Ball
This is the best alternate ability of the Sticky Explody Ball. It deals 75 damage to any plant nearby, and you have still have two in stock! Even if its has less range, I still recommend using it because of the damage. Rating: 10/10.