Yeah, you all make good points. I guess at this point it all comes down to a matter of preference. I'll hold to my stance on the matter - I'd prefer that he doesn't have a jet form.
Anyway, moving on with the discussion. I suppose I should mention that I've never been a competitive Smash player, and I have no idea what should go into a well-rounded moveset or be considered for the sake of balance. A lot of technical aspects about playstyles and character types will probably go over my head, so all I can really offer as ideas for movesets are things I think would be cool.
The first thing is that I think he should have at least one gun, bomb, and pod, since that would be in every robo's arsenal. I can't think of any good specific weapons at the moment, I might have to bust the game back out to brush up on some details and pick out some good weapons. I can think of two right now:
Blade Gun: This gun is shaped like a large sword, and shoots sword-shaped projectiles. However, I'd want this for some of the A button moves and , as mentioned by Solbliminal, modify it to be used for close range attacks. Rather than use it as a gun, he could just temporarily equip it for one of his moves and smack people with it, like a regular sword.
Trap Gun: My favorite gun from the games by far, though honestly I don't know if it could be done in P:M. This gun shoots a spread of tiny, harmless projectiles a great distance away from the user, where they float in place. After a few seconds the projectiles dramatically increase in size, then come flying towards the nearest enemy. I guess it would be a little like throwing a motion-sensor bomb that doesn't hurt people on its flight path. And instead of blowing up when someone steps on it, it comes towards enemies of its own accord. So... I guess, not really like a motion-sensor bomb at all. But hopefully I've conveyed the idea well enough.