Wow. I thought Sonic boards were bad, lol.
I was quite suprised at IvanEva's chart in Tactical discussion bumping this up to a major disadvantage. I don't agree with it at all, that charts a joke though.
What's difficult against ROB is to approach. Retreating fairs as well as ftilt keep usual bair tactics at bay. It's not like he's approach either, he is the projectile spam prince after all.
ROB is one of those characters you just can't edgeguard. With big distance on his recovery and being able to attack out of it you'll be hard pressed to gimp him. Without these gimps, expect ROB to live for a LONG time.
ROB has a faily easy time killing Jigglypuff. Nair is slow as but dsmash *****.
Thankfully, he's a big target, so dair -> rest is fairly effective, even if he lives higher than most due to his weight.
Also, he's REALLY slow in the air. With the exception of uair and fair all aerials are easily avoidable and punishable. Factor in the horrendous starting and ending lag on his dair, and you'll discover it's a real blindspot. Jiggz' uair isn't great, but oh well you get what you're given.
To be honest, I think this is just a disadvantage, not a big one. Just make extra use of your aerial game and you should be ok. I don't know much about this match-up, as I usually go Sonic against ROB. :\
Lol, I think this is my first post in Puff boards ever even though I second him.