John's point was that he had ice powers, you can pretty much do anything with that. Gamewatch also did have a lot to draw upon. R.O.B. had little to go on but he is a flipping robot, so I suppose that makes it pretty easy. Duck Hunt Dog has nothing to go on, and he is just a plain dog.
I came up with a moveset for Duck Hunt Dog. There's one move that was inspired by Wolf Link's basic attacks since they are both canines. There's like a couple moves loosely inspired by Banjo-Kazooie's Rat-a-Tat-Rap and Beak Barge involving the duck. The rest are made up and the most of the specials were based on how we played Duck Hunt.
[COLLAPSE="Normal Moves"]
A+A+A
The dog bites two times and then chases his tail around once.
Side+A
The dog grabs a duck by its neck and swings it around like a rubber chicken.
Up+A
The dog tosses a duck up in the air. The duck spins in place and pecks enemies around.
Down+A
The dog crouches and scratches in front of him. This move can cause the opponent to trip.
Running A
The dog runs on all fours. The duck lunges over the dog's head and pecks repeatedly.[/COLLAPSE]
[COLLAPSE="Smash Moves"]
Smash Side+A
The dog points his finger to the side, directing the hunter, the person playing Duck Hunt with the Zapper, to shoot there. The gunfire explosion appears just beyond the tip of the dog's finger.
Smash Up+A
The dog points his finger above his head, directing the hunter to shoot there. The hunter from the fourth wall shoots just above the tip of the dog's finger.
Smash Down+A
The dog points his finger down at the opponent's feet, goading the Duck Hunt player to "make them dance". Gunfire explosions appear on the ground just beyond the dog's finger.[/COLLAPSE]
[COLLAPSE="Aerial Moves"]
Air A
The dog tosses a duck in the air. The duck quickly flies around the dog, pecking nearby enemies.
Air Forward+A
The duck lunges out over the dog's back and pecks repeatedly.
Air Back+A
The dog does a quick back flip and as the dog is turning upside down, a duck quickly lunges out to peck. This one is useful as a Meteor Smash.
Air Up+A
The dog holds onto two ducks by their feet. The ducks flap wildly, attacking nearby enemies with their wings.
Air Down+A
This is a stall-then-fall move where the dog pounces on an opponent and they fall down to the ground together with the dog on top.[/COLLAPSE]
[COLLAPSE="Throws"]
Grab
The dog uses his chain leash to reel in an opponent. The leash can also be used as a tether recovery if needed.
Pummel
The dog holds the opponent by their necks and bites them in the face.
Forward Throw
The dog bites the opponent and shakes his head like the opponent is a rag toy and then tosses them away.
Back Throw
The dog uses his chain leash to whip the opponent overhead behind him.
Up Throw
The dog gives the opponent a heave-ho and then two ducks carry the opponent before the duck hunter shoots the opponent down.
Down Throw
The dog pounces and then mauls the opponent.[/COLLAPSE]
[COLLAPSE="Special Moves"]
B: Trick Shooting
This is based on how the second player is able to control the duck with the NES controller plugged into the P2 controller port. The dog pulls out a duck and the duck begins flying. As long as you hold down the B button, you retain control of the duck's flight path with the control stick but the dog is immobile during the flight. When you want the Duck Hunt player to shoot down the duck, simply release the B button. This move is useful for shooting out-of-reach enemies above or below solid platforms - for example, the dog is on the bottom side of Spear Pillar and Pikachu is on the top side of said stage. Guiding a duck from the bottom side to the top side and releasing the B button near Pikachu would hurt Pikachu when it is caught in a powerful gunfire explosion. Very tricky, indeed.
Side+B: Clay Shooting
This is based on the Clay Shooting mode in Duck Hunt. The dog tosses a clay pigeon like the magician and the bunny girl did in Barker Bill's Trick Shooting. You can control the trajectory of the clay pigeon with the control stick. The person who is playing Duck Hunt from the fourth wall shoots the clay pigeon when it collides with an opponent. This is a simple projectile attack with excellent range and decent knockback.
Up+B: Fly Away
The dog pulls out two ducks and hangs on to their feet. The three of them then fly away together. When the dog is flying with two ducks, his flight is speedy and lasts longer. When the dog gets hit while flying with two ducks, he loses one duck. When the dog is flying with only one duck, his flight is slower and lasts shorter. When the dog gets hit while flying with one duck, he loses it and he is unable to fly again until he lands on the ground. When the dog is flying, you can control the flight path with the control stick.
Down+B: Laugh
Many people always wanted to shoot the dog for laughing at them. How is this translated into a Smash move? First, the dog faces the screen and laughs when you press Down+B. As soon the dog laughs, the hunter from the fourth wall immediately shoots the dog. Now, what makes this move a high-risk, high-reward move is that if the dog is overlapping with an opponent when he is laughing... that opponent suffers an one-hit KO because the duck hunter shot that character instead of the dog. If the dog is not overlapping with an opponent and he is laughing... well, he suffers 10% damage and gets stunned for a second. This technique is not recommended for beginners.
Final Smash: Open Season
This move lets you play as the person who is playing Duck Hunt. You are given three shots, just like in the original game, and each shot can one-hit KO enemies if your aim is good. The NES Zapper appears out in front of the screen along with the crosshairs that you control with the control stick. Press the B button when you want to shoot your opponent. Sounds easy, right? Wrong. Dozens of ducks are flying back and forth all over the stage, making it difficult for you to aim at the enemies. If an opponent is shot, the dog appears out from the grass holding that opponent. If you failed to shoot an opponent, the dog laughs at you when the Final Smash ends and then you retain control of the dog.[/COLLAPSE]
There's also this
video where the people who worked on a fan-game called Super Smash Bros. Crusade and they actually put in Duck Hunt Dog as a playable character.