I'mma throw in my 2 cents, since there's nothing here on my main.
oh, and before I go on with my post, it might be a good idea to link to the details of the people who post, that way people will be able to read why a move is good or bad and not just guess from the color.
Moveset
1 Robo Beam
2 Wide-Angle Beam
3 Infinite Robo Beam
1 Arm Rotor
2 Reflector Arm
3 Backward Arm Rotor
1 Robo Burner
2 Robo Rocket
3 High-Speed Burner
1 Gyro
2 Fire Gyro
3 Slip Gyro
Neutral Special:
1 Robo Beam: this is your bread & butter when it comes to booping like a robot. pierces through enemies and has a decent angle while dealing a good amount of damage.
2 Wide-Angle Beam: by what I've seen, the only main difference between this and the standard is the damage sacrifice for angle output and speed. its downright ridiculous! a bit harder to control, but once you get it, you can literally stare down at your opponents to keep them from returning to the stage.
3 Infinite Robo Beam: personally the worst of the three. this is basically a shorter and slower version of the falco laser but with the ability to angle it. it has the same angle as the standard and a slightly longer startup time, but you can always shoot it (and considering the other two lasers have a 2 second charge between empty and lvl 1 laser, it's not that bad of a tradeoff.) still, it has the range of roughly 2/3rd of FD. damage is as bad as the wide angle variant and it loses its piercing ability.
Side Special:
1 Arm Rotor: it got a great buff from its brawl counterpart, so now it's a viable move! it has a multihit spin followed by a huge uppercut with great knockback. it also has a small reflector hitbox at the beginning of the move to catch projectile users off guard. and to top it all off, you can move during the entire duration of the move just in case they try to vector away.
2 Reflector Arm: lose the movement to make your spinning arms into a full reflector! definitely a great counter against faster projectile users because it has a shorter startup lag than the standard. in the air, it causes you to hover for a moment before slowly falling down. it's actually a very good edgeguarding tool, completely nullifying tethers, and due to its constant knockback and hitstun, its very hard to recover from this attack form below.
3 Backward Arm Rotor: I honestly can't find anything good about this move... horrible reflector, horrible damage, and horrible lag. it flips people over like a mario cape, but since it also hits, it only ends up helping enemies recover by refreshing their up specials. unless someone finds a crazy good use for this, its best to avoid it.
Up Special:
1 Robo Burner: your standard flying booster. its a bit slow and clunky in the air, but you can act out of it at any time to attack. it's a very good recovery, though if you don't mix it up with attacks you will be very predictable. not to mention that you need to be on the ground for a few seconds before you can replenish your robo-fuel.
2 Robo Rocket: you only get one super boost. the vertical distance is great and it actually has a secret weapon installed in it. the moment you launch, your robo body becomes a meteor smash! it's great to catch people off guard and get a very early kill, but smart people will try to footstool you. its greatest downside is the fact that it still works on a fuel system, so getting hit mid-flight will not refresh your move, causing you to lose a stock most of the time. not only that but you can't act out of it until the move is done. a very high risk considering that ROB can tank so well due to its weight and the ability to fly back from what could have been death for most other characters. it might be good against certain matchups, but its a huge sacrifice compared to the other two.
3 High-Speed Burner: this is exactly the same as the standard, though you sacrifice the amount you can stay in the air, for insanely good horizontal and vertical mobility! this is very similar to the brawl version, but with less fuel. honestly, between this and the standard is just preference.
Down Special:
1 Gyro: your standard non-edible spinning toy that can destroy opponents if used correctly. use it as a projectile, a trap set up, a decoy, and extra hitbox, even as a shield from projectiles! the difference between a good ROB and a great ROB is how they use their gyro in battle.
2 Fire Gyro: the launch from the move is much shorter and its lifespan on the field as it spins is smaller, but it's great for racking up damage. the only problem is that the launch also has longer end lag. its way better as a throwable item though.
3 Slip Gyro: the weakest of the three when it comes to power, but this gyro is even more slippery than diddy's bananas! the fact that it does not disappear when touched makes it a dangerous weapon for characters that prefer to run on the stage. once it has done its job of tripping, you can pick it up and throw is as a regular gyro for slightly less damage. the way it shoots out is also pretty interesting, sliding on the ground and able to dodge some attacks or projectiles to slide under the opponent and trip them. the distance is shorter than the standard but longer than the fire on the ground, and virtually the same as the standard in the air. endlag on the move is also the same as the standard. Sakurai sheds a tear of joy every time someone trips on a gyro.