I know this thread hasn't seen much life, but I took the time to buff Duck Hunt's Wild Gunman special move last night.
What I basically did was increase the damage and knockback that the gunmen can deliver. Originally they struggled to KO even Zero Suit Samus, but their shots have been buffed up enough so that they're able to KO someone as heavy as Mario sooner than before. I did some thorough tests with the buffs to see how quickly Mario gets KO'd on an Omega Form stage, and the results were as follows...
Gunman | KO% on Mario with Wild Gunman | KO% on Mario with Quick Draw Aces | KO% on Mario with Mega Gunman
| 277% | 331% | 72%
| 231% | 276% | 63%
| 215% | 261% | 63%
| 122% | 140% | 35%
| 167% | 199% | 49%
And yes, Mega Gunman received a significant buff in that the gunmen deal greater damage and knockback than the default Wild Gunman special move. Because the gunmen are very slow to attack, their shots have been buffed up to a point where they're almost comparable to Little Mac's KO Uppercut; they can't 1-hit KO, but the shots can still pack a punch with their knockback. However, the shots are still blockable, so if you can't defeat the giant gunmen quickly enough, you can just shield off the shots. Still, the buffs make Mega Gunman far more rewarding to use, as it's normally quite useless to use on offense.
Basically, the buffs go as follows...
Wild Gunman
Increased damage and knockback. Sombrero gunman now has KO potential.
Quick Draw Aces
The gunmen deal 5% more damage with their shots, but the shots have less knockback to compensate for their fast speed. Sombrero gunman can still make KOs, but KOs later, due to the decreased knockback.
Mega Gunman
The gunmen deal 10% more damage, and their knockback is drastically buffed as well. The buffs are made to compensate for how sluggish the gunmen are with their attacks. Sombrero gunman is the most dangerous, being able to KO even Bowser before his current damage reaches 50%.