Dr Gero has powers that are pretty skilled. Even when Goku turned into a Super Saiyan he wasn’t fazed. His power level is incredibly high and he can take down most characters in the blink of an eye. Pan is a proud saiyan warrior, but not even she can take down someone of Gero’s level. Dr Gero wins.
DReager1.com 
Dude Doctor Gero got his ass handed to him by Piccolo before he even fused with Kami. Pan is at least strong enough to whoop Frieza pretty good. And piccolo by then might have only gotten as strong as Friezas final form when he used 50% of his maximum. I have to say Pan wins this.
This is one of the closer DBZ fights. I’m just not too sure. Dr Gero wasn’t scared of SSJ Vegeta (At first anyway) Pan’s strong, but I’m not sure if she can take down Frieza. Even if she has the power she lacks the fighting experience right now. As an Android Dr Gero probably has a lot of that. Also she would probably shoot some energy blasts at first and make Dr Gero even stronger. Of course a new DBZ game can always switch this (Because sometimes they invent new super forms, so if Pan ever gets Super Saiyan this match almost definitely switches) BTW you can also request battles if there’s ever one you’re in the mood for