I actually co-main both ROB and Samus. I generally beat Rubba Prime, one of the better ROBs in our Region, all the time with Samus, and I beat Minty's Samus with ROB both of the sets we've played. I personally think this MU is even-ish, but very, very annoying for Samus. She constantly has to be on-point with her recoveries and spacing and whatnot, because regaining a lead in this MU is a long and arduous process.
Always be on the look-out for ROB's instant air-dash. All of his aerials are minus on block, so if he goes deep on your shield, you should easily be able to escape and/or punish. Also, consider taking ROB's top when he puts it out too far from himself but close to you (you can simply air-dodge or waveland through it and you will pick it up). Samus has a very good item toss, and between zair (air-dodge + A so that you don't just drop the top), all of her specials, and crawl, she is actually pretty capable of holding her own while holding onto it. On top of that, ROB won't be able to spawn another top while you're holding it (similar to Diddy's banana). Alternatively, you can throw it up in the air to keep it in play, make it yours, and have access to all of your moves. However, when using it, keep in mind that ROB has a dashing reflector. Whenever I play ROB against people who grab my top, I generally reflect a lot more to approach and make life hard for my opponent. For that reason, I wouldn't throw it in neutral against a grounded ROB with some distance between us. The moment he jumps, though, you can stuff all his options because he doesn't have an aerial reflector.
Zair is godly in this MU. It goes through the top and stuffs ROB out of his air-dash. Pretty much the only thing it loses to is his laser. I think you should use that move a lot more.
Now this is up to your playstyle, but you may want to look into using ice mode, especially when ROB is at high %s. Dthrow > usmash will catch anything that's not good DI, which will still land him on plats at high %. Usmash also covers plat techs very well. Finally, usmash can stuff him out of his air-dash options if timed well. Fair is useful for edgeguarding since his boosts are linear. More useful for edgeguarding, however, are her ice missiles. Super ice missiles are faster than super fire missiles and homing ice missiles target ROB much better. Since his recovery is so linear, if he doesn't recover high, ice homing missiles can really make his life hell. Removing even just one boost from ROB severely limits his options.
1:31 - I wouldn't DA ROB until he's at high %'s, especially a CC-heavy one like DF. Both of these chars can easily CC dsmash the other for DAing below high %'s.
1:50 - Even though you are able to nair through the gyro, I definitely wouldn't have FFed it here. I don't know why DF didn't simply usmash you here, since it's a fairly easy reaction and it would have blown through your nair for a definite kill. Basically, trying to force your way on top of ROB at high %'s is always bad. Between usmash, utilt, and uair (nair too), he will always win and probably either get a combo or a kill for it.
1:59 - Not sure if you realized that you didn't have a DJ, but why didn't you just tether here? Ftr, ROB only has 3 aerial boosts. He burned one of them plus his DJ going after you and he got hit by a bomb. Burning more would have severely risked his own survivability, so he had to return. This is when it's time to FF air-dodge tether because he can't stop you. Even after missing that opportunity, you can still tether if ROB is just going for ledgehogs. It seems that you tried to catch ROB as he refreshed his invuln, but with tether, you would have simply stolen the ledge from him. From that angle, it is actually very awkward for ROB to do anything about it.
2:10 - Same deal here. ROB can't really stop you from tething (although he could punish the forced hop). That aside, I'm not sure why you didn't just go onstage with the upB and take your punishment.
2:41 - Just DI away here (both the throw and the uair). Holding in lets ROB chain more uairs. Going away will get you fair'd, but that's less damage and a much greater commitment for ROB.
2:48 - Personally, I think you should missile a lot less since DF seemed to be catching on to the fact that he could reflect them for a free approach. However, perhaps if you missile, you could immediately crawl afterwards to duck under the reflected missile?
3:09 - I believe you got hit by the top because you waited before ledgejumping, so you didn't have enough invuln. In this case, you should have just refreshed your invincibility since ROB was too far away to be a threat. After that, a ledgejump would have been fine, or you could have hax-dashed to grab the top and be back on the ledge with invuln once again.
3:27 - In this particular position, I think you should have drop-through naired. ROB's recovery options were pretty limited (they always are when he's coming in low), and almost all of them would have lost to that nair.
Unfortunately, I could only look at the first match. It's 5 AM as I type this, so I'm pretty tired, lolz. I hope this helped. I like watching your style of Samus. It's pretty aggro and 'gives no quarter'.