Dr Gero has some knowledge of Frieza from making Cell. But not Mecha Frieza.
Mecha Frieza, pretty easily. Considering Piccolo was capable of easily dealing with Gero after the three-year training period and should still have been weaker than Frieza before fusing with Kami, I couldn't picture the Red Ribbon Army android prevailing here.
Piccolo was never stated to be weaker than Friezqa. Infact Krillin feels he is comparable to a Super Saiyan
Chapter: 346 (DBZ 152), P12.4
Kuririn: “He’s st-strong…! What kind of training did Piccolo do…And he’s not even a Su-Super Saiyan…”
Mecha-Frieza still has a chance. Not sure, so I say its a 50-50.
@supernova7005: His reaction was more surprise at how easily Piccolo could dispatch Gero. Gero's fatal flaw was that he never accounted for the significant power upgrades that the Saiyans and Piccolo gained during their travels to Namek and the timeskip following Cyborg Frieza's defeat. Frieza could at least compete with Goku's SSJ form for a time before it eventually took a toll on his ki reserves whereas 19 and 20 were both being thrashed by Goku and Vegeta as SSJs.
@Dream: Goku was easily beating 19 because he trained on planet Yardrat, and further for 2 years with Piccolo and Gohan. He was even stronger than Future Trunks, who easily defeated Mecha Frieza.
Btw 20 should be stronger than 19 as Gero was the one who created him, and he because he wants 19 to obey his commands
@supernova7005: No. Gero had made projections on the power levels of Goku and the Z Fighters based on his initial assumptions on their growth from witnessing them up to their battle with the Saiyans. He never accounted for the exponential power increases that Goku, Vegeta and Piccolo gained from either their SSJ transformations or assimilating with another Namekian. The additional training wouldn't have been necessary for those three to deal with 19 and 20.
I think that Dr.Gero isn't as powerfull as Mecha Frieza not even Frieza 100% but he would quickly close that gap with his advantages. Frieza is a hothead, when he's mad or frustated he starts spamming planetary energy attacks like he did against Goku and Trunks witch is very bad against Dr.Gero who can absorb energy. Dr.Gero as an android has a very strong grip, Android 19 showed that when he held Vegeta by his arms, and while Vegeta did break free it took some effort to do so and after Dr.Gero fled he told Krillin to give him a senzu bean because apparently in that short amount of time Vegeta was weak enough that Dr.Gero could handle him if he called the bluff like Piccolo said, so if Dr.Gero manages to sneak up on Frieza and gets a hold on him like he did Piccolo than its pretty much over and i think that he can pull it of, afterall he did it against Piccolo and Frieza was tricked plenty of times in his fights.
They are also in character witch is bad for Frieza because he tends to show off and starts blasting away and doesn't take his opponents seriously. I think that Dr.Gero can win if he plays it smart. Close battle.
Gero wins this. Vegeta did beat 19 but afterwards didn't think he had enough power to go against Gero and instead resorted to bluffing, Vegeta was said to be stronger than Goku at that point who two years ago was stronger than Trunks, that Trunks destroyed Frieza with ease. Piccolo is weird, he went from getting his ass handed to him by Nappa to fighting on par with 2nd form Frieza in a single power up, I honestly wouldn't be surprised if he was near on Frieza's level by the time Android saga came around.