Alright let's see, both R.O.B. & G&W have been covered in the matchup thread... however the guide is still in the works, and maybe reading the thread just won't do.
From my point of view, you have to play Mr. Game & Watch very defensively (I'll start with him first since I know this matchup better). You'll probably have to play similiar to how you would play Olimar. Since neither you nor G&W have a way to really force either one to approach, you can just sit tight (as Sonic, am I insane?!) and let him come to you. The reason being is because G&W's moves are safe to use to counteract any approaches Sonic has in his arsenal, but his options get limited if he is approaching you.
It's like playing a MK to a degree, you have to bait attacks and punish accordingly. You can't get him, not with aerial or smash attacks (freaking spammable moves), and you can't miss an opportunity.
As for R.O.B., you will have to play aggresively, yet stay passive. R.O.B. has a blazing fast DSmash, which if it wasn't used OoS so often by R.O.B.s, would probably kill you. Let's see now... oh yes, don't stop moving in this match, R.O.B. has a bunch of stuff to hit you if you don't move around, like Gyro's, Lasers, powerful attacks like Bair, USmash, Nair, Dair (you shouldn't be getting hit by this anyway), and then there are his throws which is telling you you are either getting predictable if he is getting you, or you aren't running around. Now while you do have to stay on the assault, you can't go rushing in recklessly. You gotta precise with your attacks.
Unless you tell me what specific problems you're having with these two, this is all I can tell you. BTW R.O.B.'s recovery is really punishable, make use of whatever you got.
