ROB is currently underrated a bit imo
In terms of matchups (in order within tiers):
Hell matchups - DDD, MK
Very hard matchups - Falco, Lucario, Snake
Tough matchups - Insert a bunch of random mid tiers and others like ZSS, Toon Link, Olimar, Pikachu, etc
Where ROB however shines in matchups is that he beats both Diddy and Ice Climbers, two huge tournament threats, especially since both of these characters are some of the ones that give MK the most trouble (though MK still beats them
)
Beyond Diddy and ICs ROB has a bunch of other good matchups for him that's great to have, such as Marth, DK, Wario, and Kirby - and I believe he wins all 4 of those matchups.
People like to bring up GaW as being a ridiculous matchup for ROB but that's not true at all, get your mind out of the '08 ROB mindset lol, ROB doesn't do worse than go even with GaW. I've beaten Vinnie in tournament recently, and in a crew battle @ Columbus we did in a hotel room I went up 3v3 stocks against Vex's GaW and 2 stocked him to name a couple of recent examples.
Another problem with ROB matchups wise is that he doesn't **** anyone really. Even bottom tiers can be a tough battle for him, despite winning. Ganondorf is surprisingly harder than you would expect lol, and Yoshi does probably the best on him out of any low tier matchup.
Strengths/Weaknesses:
ROB has so many amazing traits, but it's like every one of them has a big ol asterik on it with an but clause that makes it terrible lol
ROB's recovery is amazing and he can use any aerial out of it... BUT
-You can't air dodge out of it
-The upB does no damage itself
-There is a short period of immobility the moment you use it
-You run out of gas
ROB has two great projectiles.... BUT
-Laser has a long start up lag, so you run into a lot of examples such as when you laser a Snake, and if you get a grenade thrown at you, the laser you shoot will explode in your face. The lag is long enough that you start up the laser before the grenade is on it's way to you (though it's not enough time for Snake to punish on command thankfully)
ROB is a heavy weight character.... BUT
-Has very low gravity making him fall slowly which is AWFUL which makes him die off the top at a lower percent than a character of his weight slow, and get juggled very easily. Think the same mechanics of Samus in Melee
ROB has a great glide toss and has a lot of options out of it... BUT
-Can't spawn a gyro into his hands, he has to shoot it then pick it up
ROB can recover under the stage like gliders can... BUT
-Running out of gas can make this extremely risky, and there are some invisible wall glitches on stages (the one I know of is on Smashville but I wouldn't be surprised if there are others). If you upB hugging the top of the bottom of the stage (which makes sense to get to the ledge the fastest), at the end ROB will bounce backwards as if he hit a invisible wall which essentially kills you.
ROB's upB fully carries momentum (only character to have a move that does this I believe) which opens up a lot of new abilities, especially out of glide toss.... BUT
-It doesn't cancel momentum at all which can sometimes hurt recovery
ROB has a reflector... BUT
-It is god awful slow with an extremely small reflect box
Other strengths:
-Very good tilts
-usmash is very strong
-uair does A LOT of damage for an aerial drill move
-nair covers a large area which is great for covering rolls/techs since a single nair covers 3 of 4 get up options (nair beats get up attack, stand up, and roll towards rob, while it only misses to connect with the opponent rolling away)
Some shortcomings not mentioned yet:
-ROB has a terrible time killing. Nair won't kill for a while if it's staled, usmash is hard to hit with, and uthrow can be DI'ed easily to survive until about 180%-190% on medium weight characters
-ROB is a huge target. The physical model and hurt box of ROB is huge. He's a giant easy target for lasers and projectiles, and makes recovering an even harder task than it should be.
Tournament Placements
Unfortunately theres a bit of a skill gap after myself, T0mmy, and Stingers, but it doesn't really matter that much. There's some other ROBs out there that get some good things here and there, but there is a clear skill gap after the three of us, and Stingers technically mains MK lol, but used to main ROB and still uses him sometimes and is still very good with him. There are so few ROBs that it's tough to get tournament results to prove what he can do. Furthermore, get a bracket of MKs and DDDs and your ****ed, seriously lol
However, throughout my adventure of maining ROB I have garnered tons of awesome results that people would not expect. I've been ranked on the PA power rankings every single season never falling below 5th, and reached as high as 2nd two times (currently ranked 2nd to Squall).
In tournament I have beaten Logic/Pyronic~Star (Olimar), Candy (Snake), Omni (MK), Rogue Pit (Pit), Lain (ICs), Takeover (Snake), GDX (Diddy), Xzax (MK), dmbrandon (MK), Will (DK), Smurf (MK) and like a million other people
I've also taken a ton of players to third game consistently such as ADHD (Diddy), Blackanese (MK), Shadow (MK), Kingtoon (Toon Link), Orion (MK), NinjaLink (Diddy/ICs), NEO (Marth), and a lot more
I also have a handful of money match wins versus players like Seibrik (MK), Wes (Sonic), and idk like a million people, my mind is drawing a blank
Even further though to make it better is that ROB does amazing in doubles. Half of the mad batchups he has are gone. No more problem with Falco, DDD is no where near as bad, MKs aren't an amazing threat anymore, etc.
I have a bunch of doubles achievements such as beating:
Anti and Will with Dabuz (Olimar)
NinjaLink and Jash with Dabuz (Olimar)
Keitaro and Orion with Stingers (ROB)
Keitaro and Malcom with Vex (GaW)
Inui and Shadow with ADHD (Diddy)
Kingtoon and Squall with Vex (GaW)
and idk like a million more things
Other ROBs have some noteable accomplishments like T0mmy's recent beating of Jem and Felix but tbh other ROBs don't have the kind of results I do.
Tier List Placement
ROB either belongs in the tier he is currently in or in the lower run of high tier. I'm not sure if it's that he deserves to be moved up, or if some of the high tier characters deserve to be moved down like GaW. Either way, ROB should be a bit higher, even if it just means being higher in the top of middle tier. Despite some of his awful matchups (mainly the trifecta of DDD MK and Falco), the fact that he beats tourney threats such as Wario, Marth, Diddy, and ICs is toooooo valuable to have in tournament.