R.O.B.'s playstyle is characterized by his long juggles into aerial followups, and deep offstage edge-guarding. R.O.B. has more success when focused on low-percentage off stage edge guards than in on stage brawling. R.O.B. has a high durability due to his heavy weight and flexible recovery, which somewhat compensates for his difficulty winning neutral.
R.O.B.'s forward smash and up smash are strong finishers at high percents. R.O.B.'s up smash is useful for juggling fast fallers at low percents and killing light characters off the top blast zone. His forward smash comes out quickly, but has limited range despite its disjoint in front of R.O.B.. R.O.B.'s down smash is one of his fastest moves, and also a primary defensive option for close opponents attempting to pressure R.O.B.. It hits multiple times and pops up opponents for easy aerial followups.
R.O.B.'s up tilt is useful for juggling on characters with low gravity, or at higher percents. R.O.B.'s forward tilt is useful when R.O.B. has to engage with a character geared for hand to hand combat. Its quick speed and surprisingly long range are ideal when opponents are too far away to grab, but too close to set up for a stronger attack. R.O.B.'s down tilt comes out close to the ground and sends opponents at a low angle, making it good at shield stabbing taller characters, and punishing opponents who fail to sweetspot the ledge. R.O.B. can use this move in succession to pressure an opponent in shield. In general it has similar utility to Marth's down tilt.
R.O.B.'s back, down, and neutral aerials make use of his booster, and accordingly are slow but strong. His back aerial is an excellent tool for onstage edgeguarding. Its large hitbox and high power throughout mean that precision is not required to successfully land the move. R.O.B.'s down air powerfully launches foes downwards, but can be difficult to successfully land due to stricter timing and the inherent risk R.O.B takes by being above an opponent. R.O.B.'s neutral air swings his booster around him in a full circle, and launches opponents hit by it upwards for aerial followups. R.0.B.'s up air has him release multiple blasts from his eyes in an arc above his head. This move comes out quickly, and sends opponents out at an angle, which makes it useful for forcing airborne opponents off stage. This move is especially powerful against fastfallers due to the ease R.O.B. has comboing into it, and the arc at which these characters are launched, allowing for edgeguard opportunities and K.O.ing opponents outright in some situations. R.O.B.s forward air is his fastest aerial and has high damage scaling. It is useful at low percents to flinch opponents attempting to recover offstage, and as an approach out of a horizontal Robo-Booster.
R.O.B.'s up special and aerial side special have been combined into the Robo-Booster, allowing R.O.B. a short boost of speed three times in any of three directions. This allows him flexibility in his recovery, but since he does not recover his three boosts until landing on stage, one successful edgeguard can leave him unable to recover in a similar manner to Yoshi. Grounded, his side special is an advancing spin. Though useful as a surprise attack, it is unsafe on shield and punishable if overused. It is useful if R.O.B needs to rush to the ledge to intercept a recovering opponent as the leading edge of the spin hits low to punish opponents who recover on stage or fail to sweetspot. R.O.B.'s down special produces a Gyro which can be launched at opponents and will spin for a while and flinch opponents that touch it if not picked up. Often it is better for R.O.B. to pick up the Gyro as it gives him access to several advanced techniques based around aerial glide tossing which can improve his otherwise somewhat lacking movement. R.O.B.'s neutral special is an angleable bouncing laser fired from his eyes. The laser is not destroyed on contact with a character or object and will continue traveling to it's maximum distance. It charges over time and has three distinct power levels. Uncharged the laser does not travel very far and is of limited use. At the second stage the laser travels quickly and deals little knockback. It is able to flinch opponents attempting to perform an action and can K.O. opponents attempting to recover. Fully charged the laser travels slower, but still fairly quickly, and deals significant knockback to all opponents it hits, killing at higher percents. The fully charged variant can be dangerous to use against foes with reflectors as the slower speed gives them more time to react, and if hit by a reflected laser, R.O.B. can be easily K.O.ed due to the high power of the laser after reflection and his inability to react due to the length of his animation.
R.O.B.'s throws are straightforward, but practical for the rest of his moveset. Up throw and down throw both have chaingrab opportunities on many characters and up throw scales into a kill throw at high percents. Forward throw and back throw have low knockback scaling giving them limited ability to K.O, but allows them to launch opponents off stage for an edge guard even at low percents.
R.O.B does poorly against characters with multiple jumps, or otherwise able to outmaneuver him in the air, furthermore he is susceptible to being edge guarded himself, making these characters very difficult to engage off-stage. Characters with better zoning tools than R.O.B. can force him to approach, making his slow movement an even greater problem. His lack of options out of shield make him somewhat predictable and vulnerable when under shield pressure. R.O.B.'s anti-air capabilities give him favorable match-ups with fast falling characters and characters who approach from above. Due to his high weight he is able to crouch cancel very effectively and successfully defend against characters focused on fast, weak attacks. Most striking is his offstage edge guarding which gives him very strong match-ups against characters with linear or slow recoveries.
Changes from Brawl to PM
In transition from Brawl to PM, his aerial game has been greatly improved; all of his aerial attacks execute much faster and he now has a new recovery. R.O.B.'s no longer has to stay on the ground to recharge his recovery, making his aerial game safer than before. It has been broken into 3 segments. R.O.B.'s side special now funtions as a horizontal recovery segment in the air, while works as a quicker version of Arm Rotor that lunges forward on the ground. R.O.B.'s new up aerial has a wide reach and is also a finisher. R.O.B.'s poor KO ability in Brawl has been well addressed overall. As a whole, R.O.B. has been buffed in PM.
Grabs and Throws
Up to date as of version 3.6.
In competitive play
Z-Secret Costume: GameCube R.O.B.
R-Secret Costume: Nintendo 64 R.O.B.