I've now made a video with all of Duck Hunt's custom moves. It can be found here:
I haven't tested these thoroughly yet (kinda hard when only standard are allowed in For Glory but my initial reactions are:
Neutral B
I feel like all of these could be potentially viable. The 2nd, that explodes fast, is probably the easiest and the best until you get good enough to take advantage of the other ones. The Zig Zag one is interesting since it hits quite a big area and it stays around the same area, with no chance to jump down the ledge that could happen with the normal neutral B.
Side B
I'm going to be bold and say that the standard Side B will be the one to use. After playing lots of online in For Glory I must say it's one of Duck Hunt's best moves. Fast, but still controllable since you decide when to explode and does a lot of damage as well. I don't see the other two being as useful.
Up-B
Here I feel like all three could become viable and possible counter-picks depending on what character the opponent uses. The standard is just a great recovery that ensures that Duck Hunt always makes it back to the stage. The 2nd Up B, that also attacks, gives a good extra coverage attack at the expense of a bit worse recovery, as well as the possibility of not making it back to the stage if you bite an opponent too far below. The final one might be good if the meta shifts towards aggressive edge guarding or against characters who like to edge guard aggresively, as it ensures you get back to the ledge without risk of getting gimped. It is a bit harder to control though, and not as high as the standard Up-B I think.
Down-B
Yeah, this will probably also be a counterpick, but it's too hard to say yet since we haven't fully gone in-depth in what possibilites lie in combining the can with Down-B. My initial reaction is that the last one, with the giant gunmen, probably is the best since it just stops all projectiles but the others are nice against opponents lacking said projectiles. But I don't feel like I want to comment this more at this stage, needs more testing.