Dr. Gero and Planet Namek

[Dominator]

This may have already been discussed, but I'm lazy when it comes to searching for something. If I remember correctly, the following is how part of Goku's encounter with Gero went.

Goku: One flaw, you know nothing about my battles on Namek.

Gero: Irrelevant, we have all the data we need.

As well as not knowing about any of this, he seems pretty unconcerned about some missing information. So if he knew nothing about Freeza, how did Cell know who Freeza was and how did he know his techniques (the one-finger Death Beam)?

[tealsmith]

This may have already been discussed, but I'm lazy when it comes to searching for something. If I remember correctly, the following is how part of Goku's encounter with Gero went.

Goku: One flaw, you know nothing about my battles on Namek.

Gero: Irrelevant, we have all the data we need.

As well as not knowing about any of this, he seems pretty unconcerned about some missing information. So if he knew nothing about Freeza, how did Cell know who Freeza was and how did he know his techniques (the one-finger Death Beam)?

As far as I recall, Gero mentioned taking some of Freeza's DNA when he landed on Earth. Could be completely off there though. I also recall him saying he didn't take any of Trunk's because he had all the Saiya-Jin DNZ he needed.

Of course, if his little DNA Collector/Camera Bug was present when Freeza landed on Earth and Gero watched, it would bring up the question of why he didn't recognize Goku's SSJ state, since Trunks went SSJ against Freeza, and Goku used it not long after touching down on Earth.

[Zackarotto]

Didn't he get the data from Freeza and his father when they came to earth?

Edit: Ah, tealsmith beat me to it. And did a better job, I might add.

[Dayspring]

The spy-bot that stole cells knew about Mecha-Freezer+Cold. Gero himself stopped giving a damn after the time Goku fought Vegeta, if I recall correctly. Most likely he perfected the android designs to the point where #16 was coneived. At one point, he said to Goku "You've past your prime. Even if you did in fact make progress it would be negligable.", and that's an accuracte assumption since, had the events of Namek+Trunks arrival not occurred, Goku's strength would have stopped growing once he healed. That PL would have been significantly less than 90,000, whereas #19 and #20 would have been strong enough to kill Freeza. In those three years and one week, Goku made did make a psychotic amount of progress even by Saiyan standards, so it's not surprising Gero underestimated him.

[Super Sonic]

Also didn't the cells from Frieza only happen in the timeline that Cell came from?

[Sun_Wukong]

Everything up to Freeza's arrival was the same in all the timelines, Goku's, Trunks', and Cell's. After that was when things got screwey.

[Akira]

I'd like to expand on this a bit. Dr. Gero watched Goku use the Kaioken during his battle with Vegeta. I think Gero calculated Goku's future strength increases based on that fight and that technique. I figured the Mecha bugs arrived at the detection of new ki signatures, and readily grabbed samples from Freeza and Kold. They probably scanned Trunks before he went Super Saiyan, got a negative reading for further Saiyan DNA collection and left immediately to return the samples taken from the invading aliens. The fact that Gero probably wanted those samples ASAP is most likely kept him from uncovering the secrets of the Super Saiyans in advance.

During the three years, Vegeta made his transformation in space, and Goku just trained to raise his base against Piccolo and Gohan, therefore making him that much stronger when he became Super Saiyan later on.