Eight days to a year since he was last spoken of... kinda tragic, the guy's partially responsible for the Rhythm genre as we know it. (Plugging a tagline here: "PaRappa's Gotta Believe!"
So, here's a basic moveset concept. PaRappa, being superflat (like Game and Watch, his model is constantly flattened), has a weight of 65, weighing more than only PICHU! However, his mobility attributes would be very good, although he only has two jumps, no crawling, and no wall jumping.
Let's get the Fighter Ability (what SmashWiki calls character gimmicks, which is honestly just a nicer term that I like more) out of the way: U'rappin. PaRappa starts every stage U'rappin GOOD, and there are four tiers of U'rappin: COOL, GOOD, BAD, and AWFUL. How many attacks you land, plus how well you do on his Neutral Special, and whether or not you have your Down Special active, determines whether you're going up or down on the U'rappin scale, which is listed next to PaRappa's portrait to the player's left. Dying resets your rank to GOOD, regardless of how and what rank you previously were.
- GOOD mode, the default, has PaRappa about where he should be, making his attacks plenty powerful and his mobility all around fantastic. To get to COOL, you have to land 20 hits in a row to get it to blink, and 30 more to actually achieve it.
- BAD very slightly weakens him, it's not that much but it's noticeable that he isn't as good as he should be. His attacks take a blanket 15% decrease in power and his weight drops to 62, tying Pichu. The button inputs for his Neutral Special become easier to do as well. Miss 10 attacks in a row for a warning, 5 more for a drop. He has to land 10 attacks to get back up.
- If by some unfortunate circumstance you're in AWFUL mode, PaRappa's attacks are reduced in power by 30%, his weight becomes 55, lower than even Pichu, and his mobility drops by 10% all around. The button inputs for his Neutral Special become significantly easier. Again, miss 10 attacks in a row for a warning, and 10 more for a drop. To get back up, he has to land exactly 5 attacks. Also, for Final Smashes that instantly kill over a certain percent, if PaRappa is in AWFUL mode, it counts as being over the required percent.
- If PaRappa's not even able to do well enough to stay AWFUL, he will instantly die (the hidden rank below AWFUL is nicknamed WORST) regardless of percent, location, or anything else. PaRappa is allowed to miss 15 attacks before a warning, and has 10 more once it shows up before instant death. The instant death counts as an SD on PaRappa's part.
- And for those who have mastery of the rap system, COOL mode is where PaRappa shines. His attacks increase in power by 50%, his weight drastically shoots up to an okay 85, his mobility is enhanced by 20%, and he can cancel any animation 10 frames in into anything he wants. He's a Rap God now, and you better believe just like he does. His Neutral Special does not force any button inputs, but you have to do it every 15 seconds to avoid getting bumped down to GOOD. Missing 10 attacks in a row also bumps you down to GOOD without warning.
PaRappa's normals are almost all taken from PSAS, since that gives him plenty of moveset potential to work with. So that brings up to his big 5 moves, his Specials (counting his FS).
- The Neutral Special is Rappin'. PaRappa will stand still and look above his head: above his head are 10/8/5/3 (C/G/B/A) button inputs. For the latter three levels, they can have A, B, X, Y, R, L, or Z on them (ZL and ZR wouldn't work with a GameCube controller), but on COOL they don't have any at all and you can do whatever you want given you time it right. PaRappa's head floats on by, passing the buttons: the player is expected to press the buttons at the same. Even if he gets hit, the button inputs will still work: he has invincibility (in 1 on 1 matches, it's demoted to super armor, but he can't be grabbed for the first 10 frames) for the duration of the move, and super anchoring at that: only Final Smashes and other unblockable moves penetrate it.
- If the player puts in at least half of the rap commands, then they will do a big shockwave around PaRappa and he will retain his current rank. Below GOOD, it will also allow him to climb back up to GOOD.
- Don't meet that requirement, and PaRappa will take 5% of damage, and begin to drop a level of U'rappin. This must happen twice per to drop, and for AWFUL to WORST, PaRappa must do it thrice for a blink, then twice more to die instantly.
- If the player has absolutely no inputs, or inputs the wrong command every time they did make an input, then PaRappa will take 20% damage and instantly drop a level of U'rappin.
- And if the player puts in every input perfectly, they will instantly shoot up a tier while also generating a giant shockwave around PaRappa that is far more powerful than the half version. COOL, however, requires three perfects in a row to start blinking, and two more to be unlocked (that is, 40 perfect button inputs without a single slip up).
- The Side Special is Skater Boy, his Level 2 Super from PSAS. PaRappa takes out his skateboard and goes for a funky ride. He will stay on it for 7 seconds before getting off of it. While on the skateboard, he is a hitbox and he moves much faster both on the ground and in the air. This move is perhaps PaRappa's strongest kill move, doing so at around 140% for Bowser. In the air, this move gives PaRappa a small jump when used, so his horizontal recovery is fantastic.
- The Up Special is Romantic Karate, his Level 1 Super from PSAS. PaRappa does a jumping mid-air flipkick with an outgoing 90-degree angle wave, just like in PSAS, except that it makes him jump much higher than before. Albeit, it isn't that high anyway, so his vertical recovery is not very good. Since Supers were the primary (and by "primary", I mean only) kill moves in PSAS, this move would be one of PaRappa's best finishers to a combo since Skater Boy is much more of a commitment.
- The Down Special is Boxy Groove!, his Down Special in PSAS. PaRappa pulls out Boxy Boxy and puts him on the ground. Boxy Boxy will begin to play a beat: this beat deals 1% of damage to all enemies that come in range of him every second, but that's not the main purpose of this move. No, it's how when Boxy is out, PaRappa can only lose rank through failing his Neutral Special and gains non-COOL rank points simply by being there. If things are too hectic, this guy will chip in. He also charges your FS Meter faster if it's on, but if it isn't he can't give you a Final Smash. You also have to be near him to get the benefits, and teammates get nothing.
- And his Final Smash is none other than his Level 3 Super from PSAS: Doom Box ft. PaRappa!!! This move is a cutscene attack just like it was before, except PaRappa pulls out Boxy Boxy as the trigger attack that has to hit. Aside from that, it is functionally identical to its PSAS incarnation except for being an instant kill (unless his opponents are at 100% or more).
EDIT: Also, we need a song list, but... tell ya the truth, literally all the songs should be represented. 6 from PaRappa 1, 13 from Lammy (not counting PaRappa!Stage 1), and 8 from PaRappa 2 makes for a healthy, awesome 27 tracks. CCMO's Rap, Full Tank, Got to Move, and Noodles Can't Be Beat would get remixes.
For a Spirit Roster... I have two in mind. In both, PaRappa has his own Fighter Spirit, and there are 11 Spirits. Global Series (like Hero's):
Novice: Papa PaRappa, Ma-San, Boxy Boy, Joe Chin (4)
Advanced: PJ Berri/Mooselini, Katy Kat, Chop Chop Master Onion (3)
Ace: Sunny Funny/PJ Berri, Colonel Noodle, Rammy (3)
Legend: Lammy/Sunny Funny (1)
And PaRappa 1 Only (like Joker's).
Novice: Papa PaRappa, Boxy Boy, Joe Chin (3)
Advanced: Prince Fleaswallow, Cheap Cheap the Cooking Chicken, Katy Kat (3)
Ace: Chop Chop Master Onion, PJ Berri, Instructor Mooselini, MC King Kong Mushi (4)
Legend: Sunny Funny (1)
PaRappa's colors: Default, Sunny Funny (Pink Hat), PJ Berri (Yellow Hat), Katy Kat (Blue Hat), Lammy (Black Hat), Funky Astronaut, Funky Gi and Prom King.
Now you may have noticed I don't always have Lammy represented... that's because, what if she, too, were playable? Leave it to Lammy!... later, I don't feel like it now.