Immortal

First you have to understand that Brainiac is virtually Immortal. Existing for Thousands of Years.

-- Krypton 1x06

Far beyond Krypton and even planets they consider to be advanced.

He possesses the intellectual plunder of countless advanced civilizations. He's far beyond us. And as history has proven, Krypton's current weapons are useless against him.

-- Krypton 1x06

Conquered Multiple Planets

It moves... from planet to planet conquering civilizations. Destroying billions of lives. It's known as the Collector of Worlds. But its true name... is Brainiac.

-- Krypton 1x01

Brainiac employs a massive ship as his main base of operations

Absorbs Memories and Skills of others

Voice of Rao: Is that important to you little Sundrop?

Ohna: How did you know my mother called me that?

Voice of Rao: A few of the worthy, the special ones, I take into myself. I take their memories, skills, dreams. Everything that makes them what they are. Their template, they live forever in me.

-- Krypton 1x06

Possession Keeps Sentries alive until they have fulfilled their missions

Seg-El: Is she going to live?

Val-El: It's difficult to say. Whatever Brainiac did, it appears to be keeping her alive. My concern is that, in trying to reverse it, we risk losing her.

-- Krypton 1x03

General Zod: Black Zero is of no concern. Krypton's survival is. And to protect it from Braniac, I need to know what his Sentry was doing in that communications hub.

Seg-El: She was uploading data to Brainiac. We tried to stop her, but she too far along.

General Zod: I thought we had more time. After it uploaded the data, what happened to the Sentry? Did you destroy it, or did it go dormant?

Seg-El: Hey, that it is a she, and her name is Rhom. And I'm not answering any more of your questions, and you...

General Zod: Is it still alive?

Seg-El: I don't give up my friends.

General Zod: That Sentry's not your friend. Not anymore, and if it's still alive, then it didn't complete its mission.

-- Krypton 1x04

Immune to Kryptonian blasters

[holds up a blaster]

Jayna-Zod: Not with that. Our weapons have no effect on him.

Seg-El: They might not harm him, but they will piss him off...

-- Krypton 1x07

Walks Through Fire

A Newly Infected Sentry slaps a person a dozen feet.

A Newly Infected Sentry ragdolls and kills 3 Armored Kryptonian Soldiers

Goes from sitting to standing next to someone in less than a second

A Sentry uses its cables to restrain and choke someone.

A Sentry attacks with its cables faster than a group of armed soldiers can attack.

Cables catch up to a fleeing person and drags him away

Manipulates Fire

Steals Energy from the Embryos in the Genesis Chamber

Turns a girl into a bomb

A Sentry senses are enhanced to the point where it can tell if someone is lying.

Voice of Rao: You are lying. So easy to tell with your species. Intensified breathing, elevated heart rate, the pheromone you generate. All are windows into your limited nature. There is nothing you can hide from me.

-- Krypton 1x07

Interrogates someone

-- Krypton 1x07

Carries and holds Seg with no difficulty

Brainiac was able to manipulate over a dozen people into killing each other.

Fascinating. Opposing forces with nothing in common but their obsession with power. One hoping to cling to it, the other to seize it. Now united against me. But tell me: does you fear of me outweigh your fear of each other? [gun trembling] - What are you doing? - It's not me! I swear! Whoa! whoa! Guns down! Guns down! Guns down! Such weak minds. Polluted by fear and hatred. So easily manipulated. Go on. You know you want to.

Krypton 1x09

A sentry can use their cables to hijack a person's mind and make them into their own personal drone. These drones are completely loyal to him but maintain thier own autonomy, memories and skills.

These drones are much stronger and faster than a normal person. A drone easily dodged a laser blasts.

Drones could move at blur speeds and blitz opponents.

They could also casually ragdoll and fling people a dozen feet with one arm.

One also tanked a blast that destroyed his arm which would be a typically lethal attack.