I'm saying that having Bowser Jr. transform into Shadow Mario to ANY capacity seems redundant and pointless.

I think Bowser Jr should just get into a Clown Copter and throw objects (spike balls, Mechakoopas?) and spit fireballs at enemies, it would be just like his various boss appearances. This for his Final Smash i mean.

His first appearance was Sunshine though, I think the paintbrush is more iconic.

Well true, but considering that the paintbrush thing was only in like two games (does Hoops 3 on 3 count?). He is more often seen with the Clown Car, or some other giant machine.

Eh, i just think it would be better to have the Clown Car in the moveset somewhere, Final Smash seems best (it could be his entrance as well lol), Shadow Mario is never really "fought" as a boss, you just chase him and dowse him with water.

I think I have an idea for Bowser Jr.'s moveset (assuming Shadow Mario won't play a role in it). Here it is:
Down-Special: Shoots a paintball that knocks opponents back, and if it hits the ground, causes tripping/slipping nearby. Chargeable (?).
N-special: Shoots out a red fireball (much larger and more powerful than Mario & Luigi's, but more start-up lag) that isn't affected by gravity. Goes diagonally downward when used in the air (like Ness' PK Fire).
Side-Special: Runs really fast (about 1/2 the distance of Brawl's Final Destination), then swings his paintbrush upwards (similar to Captain Falcon's Raptor Boost). This was used to hit the tennis ball from a faraway distance in Mario Power Tennis.
Up-special: Teleports using the M-shaped portal he could create in Super Mario Sunshine. He'll go in the direction the control stick is pointed, and will also have super-armor. He can also use aerials after its use.
Final Smash: Like Thundaga said, he flies around in his Koopa Clown Car, spitting fireballs and throwing down Spike Balls.

Actually his paintbrush has appeared in multiple games. In addition to SMSunshine and MH: 3 on 3, Jr. also uses it in Mario Power Tennis, Mario Super Sluggers, and Mario Sports Mix. The Brush also made a cameo appearance in Mario Kart Arcade GP.

Oh ok, i really wasnt sure about that, those two games were the only ones ive played that have it lol. I never got a chance to play those others. But yeah, i wouldnt mind if they gave him the paintbrush, i just want to see the Clown Car, as its more often associated with Jr than with Bowser these days.

Pretty much all the Koopalings as well as Bowser have been in the Clown Car. But the only person to use the brush was Bowser Jr.

This is IF he even gets in in the first place.
Anyone remember Gooey?

uh from Kirby's Dreamland 2?

Yeah he's a pretty common suggestion. Tbh I'd be more willing to see Bandanna Dee from Return to Dreamland. The one with all the fancy spear moves.

The one that was a carbon-copy of Spear Kirby from that same game? :3

He still would've made a good character, considering his possible moves and what makes him separate from Kirby.

And even if he was a copy of Spear Kirby in Return to Dreamland, it's not like we have Spear Kirby in Super Smash Brothers. If Bandanna Dee was in SSB4, he would be a very unique character with a very unique moveset.

imo the most appropriate fourth character for a Kirby rep.

The only possible Kirby reps that would be good additions imo, are Gooey, Prince Fluff (Epic Yarn), and Bandanna Dee.

Unless they somehow turned one of the helper characters from Super Star or one of the many Minibosses (like Bonkers or Bugzzy) into a playable, but i dont see that happening.