His side-B wasn't "buffed" per se. Like I said, it was an accident of the physics, but seeing as it made a previously useless move somewhat useful, it was left in.
I'll try to list all the buffs/nerfs I can remember. Don't consider this a comprehensive changelist, just the important stuff.
Buffs:
-uthrow kills a little better
-higher fgrav to allow slightly faster jumps (not the only one)
-a few Sakurai angle removals on things like ftilt and laser and ... I can't remember what else atm (universal buff)
-side-B by accident of physics
Nerfs:
-dsmash, in damage, kill ability, and combo ability
-utilt in many ways
-dthrow to not combo so well
-dair landing lag (no idea why
)
-dash attack I think maybe? I know it was fiddled with, I dunno where it stands compared to vBrawl now
-up-B due to removal of autosnapping (universal nerf)
-spotdodge/airdodge (universal nerf)
I think that's pretty much it. ROB has never needed more than minor tweaks.
NOTE: This is all from vBrawl. AFAIK the only thing he's gotten in 7.0 is the Sakurai angle removals.