And you main Peach? I dont know about Olimar vs Peach really, nobody I know mains Peach.
Anyway I was fighting a friend that uses ROB and held on to his Gyro most of the match XD basically what I did was use it to get him off the edge, then continue to bounce it off him to keep him there, while at the same time latching Pikmin onto him. This seemed to work very well because it racked his damage up high, kept him off the edge and unable to attack me while raising his damage.
Also Don't worry about ROBs Side B, which is basically his Dsmash but it moves like Luigis cyclone, Olimars Jab (the headbutt) has priority over this, along with most of his attacks.
One thing that should be a given to Olimar players is to latch Pikmin onto ROB while he is charging his Gyro, and to NEVER try and approach him while it's charging. If you continue to jump and latch Pikmin ROB will be forced to stop, and either throw the Gyro or destroy the Pikmin. When I fought my friend I would latch Pikmin, he would throw the Gyro as I came down, and use an attack to kill Pikmin so while he killed my Pikmin I grabbed his Gyro, this can be and effective technique to get a hold of the Gyro and keep it from ROB unless of course they save it for later and just kill the Pikmin but it still usually isn't that hard to get it. Holding onto the Gyro can GREATLY put Olimar at an advantage. And don't forget Olimar can duck to avoid ROBs LAZOR so with little prediction and timing you can avoid it, so by avoiding the laser and holding onto the Gyro basically forces ROB to approach you, which is probably not in ROBs favor.
^This can be howz to winz maybe?
I'm actually starting to think with some practice, and some Gyro stealing ROB can become one of Olimars easier match ups, but still a challange, maybe equal. IMO, lol.