I'll try and do a quick write up of my opinion.
His strengths are his throw combos, lingering disjoints, use of aerials/dash attack/usmash, etc to vortex opponents above him, great offstage game and great recovery
His main weaknesses are the he's forced to be an aggressive character because of his lack of fast defensive options and good projectile, and his lack of kill confirms combined with being susceptible to dying very early from rage or strong moves in general.
The general opinion of tourney-goers is the he's mid/low-mid, most relatively succesful G&W mains put him at mid/high-mid. Personally I'd put him at mid, mostly because of his abysmally bad MUs against some top 10 characters. I'm kind of a scrub tho.
The main characters he loses to are the ones who can easily exploit his inherently aggressive playstyle and lack of fast options, especially ones with fast, effective oos options (sheik, fox, diddy, sonic)
Sounds like you have the general idea of his Megaman MU. Bucket, while not being massively strong when filled with lemons, can be an effective deterrent to lemon spamming and none of Megaman's other moves are particularly troubling in neutral. Gimping G&W is p hard and Megaman's recovery is vulnerable to runoff bair/dair. I don't have much experience vs megaman but i assume usmash and dsmash punishes are effective against G&W. MU's probably slightly in G&W's favour.