Just going to repost the video description here, it contains a fair amount of information even without the video
Mostly only going over combos which I haven't seen anywhere else for R.O.B. guides.. many of these do much more damage than Down Throw-Up Air (The "Beep Boop") and can result in very early KOs for R.O.B. even without rage as he has one of the strongest spikes in the game and several setups. Spamming the Beep Boop will also result in it staling his up air which can be very problematic.
For reference the Beep Boop does 20% damage when fresh. Up Throw does an additional 2% compared to Down Throw, can combo into more damaging moves, and has the potential to combo 2 or more attacks.. Maybe time to think twice about only using Down Throw?
Combos:
Up Throw-Up-Angled Forward Smash (can True Combo):
Works on most characters with the exception of short light characters (and wario for some reason) Only works at very low percents with minimal rage. Hitting the true sweet-spot does 28% with everything fresh and can lead into a gyro or laser.
Up Throw-Running Up Smash (can True Combo):
Pretty obvious, will work up to around 30% on bigger, heavier characters in my experience. Can followup with another running up smash, up air, or neutral air.
Up Throw-Foward Air (can True Combo):
Has some followups and can SHFF into a grab or smash attack. Or you can go for the fairside b.. Can also lead into projectiles but almost on R.O.B. everything does. Even projectiles.
Dash-Forward Air-Arm Rotor (can True Combo):
With rage or at high percents this can surprisingly lead into a KO near the ledge, and is quite difficult to escape with practice. Seriously, it's not the worst move.
Up Throw-Down Air-Various Followups:
This is pretty situational and requires you to read their DI or airdodge. If a character immediately airdodges out of upthrow you can punish them with a down air, but this usually will not be a combo. This can also be used near the ledge, which can lead directly into a spike at KO percents. Can lead into an up smash, forward smash, or another down air for early KOs on missed techs or grounded hits.
Up Throw-Neutral Air-Up Air:
Works around 20-40% depending on weight. This one seems more reliable on floaty characters compared to his other up-throw combos..
Up Throw-Up Air (can True Combo):
This one can KO a little earlier than the normal beep boop on some characters.. who knew?
Z-dropped Gyro or Gyro thrown down-Footstool Jump-SHFF Neutral Air or Down Air (Untechable):
Can also potentially lead to jab reset combos or a gyro toss if you manage to grab it. If the opponent does not get up fast enough it is possible to set up jab resets with this as well.
Grab+Pummels-Falling OR Spinning Gyro-Up Throw or Down Throw-Up Thrown Gyro (True Combo):
Yeah thats a bit hard to say.. This works and does a fair amount of damage if your opponent is dumb enough to get grabbed on top of a falling or stationary gyro. The spinning gyro will rack up damage while you are pummeling the opponent. Disrespect.
Grab+Pummels-Up Throw or Down Throw-Falling Gyro-Various Followups (can True Combo):
Basically the same thing, but you throw them into the gyro instead of letting it land on them. You can jump up and catch your opponent if you read the direction the gyro hits them, but I like to just stand there and recatch the gyro.. there's not much they can do about it and they already got disrespected *shrugs*
Random Gyro Tricks:
GYRO SPIKE: Face side of the edge you're near! (the gyro's knockback direction depends on how you are facing when you through it), place the gyro near the ledge if your opponent is off stage. Most get-up options will result in them hitting the gyro and getting popped above the ledge. With quick reactions and accuracy this will true combo into a spike. Depending on the character, stage, and rage level this can potentially KO at 0%, it seems to be a kill confirm earlier before 50%.
You can also essentially do the reverse of this and face the centre of the stage, stand close to the middle and use an upsmash when your opponent tries to get up. With good timing the gyro will hit them directly into your upsmash and prevent them from hanging onto the ledge. Doing this will also stage spike anyone holding onto the ledge for too long, granted the gyro hitbox comes into contact with them.
Another potential stage spike with the gyro is to face towards the stage and drop it on anyone trying to use a tether or unsafe recovery. The gyro will hit them towards the wall, and if they are close enough to it the hit be impossible to tech.
Additional notes: Most of these will work going through platforms as it doesn't effect the knockback or hitstun, it simply makes both characters end up higher. Unfortunately many will not work on small and light characters. For characters like Jigglypuff and Kirby downthrow to up air seems more reliable than any of the higher damage upthrow combos. Wario and some other small characters are also immune to upthrow-up angled fsmash regardless of their weight.