I had something of a similar idea for an Agumon moveset some time back:
Fighting style: Agumon is a fast, mid-lightweight character with a primarily rushdown-focused strategy, though his neutral special also gives him access to some slight zoning capability. His gameplay will be hyper offensive and his attacks will all come out super fast and aggressive, but as a tradeoff he will be easily comboed and juggled due to fast falling speed. While his attacks are very good at comboing and dealing damage, he has little KO potential aside from his Forward Smash… at least, that’s how it is normally. Agumon has a special mechanic that, utilized correctly, can greatly increase his strength in nearly all aspects.
Special Mechanic — Warp Digivolution: Taking a page from
Digimon Rumble Arena 2, while playing as Agumon, special colored orbs that match the player’s shield and name color will appear sporadically across the stage, appearing at a faster rate as you deal more damage to your opponent. Agumon can pick them up just by touching them, and only the Agumon with the corresponding player color can do so. When they do, they’ll fill a special Digivolution meter on the bottom of the screen, above Agumon’s percentage indicator. When the gauge is full, Agumon will automatically digivolve to Wargreymon and stay transformed for a short time. As Wargreymon, the character gains increased damage and knockback on his moves, as well as increased weight, making them harder to KO.
Agumon’s Special Moves:
- Neutral Special - Pepper Breath: Agumon spits out a small fireball, that travels a across the screen at a moderate pace. While it has very short range for a projectile, it can deal a good amount of hitstun to allow for follow-ups. When used in the air, it travels diagonally downward instead of forward.
- Side Special - Mach Jab: Agumon quickly lunges forward with his claw extended, knocking the opponent diagonally forward and upward in a manner similar to Jigglypuff's pound. The attack only deals weak knockback, but it can be used to set up aerial follow-ups by savvy players. It travels a decent distance horizontally, making it useful for recovery, and you don't get put into helplessness if using the move in midair.
- Up Special - Claw Uppercut: A simple uppercut maneuver that recovers a good distance upward, but has next to no horizontal mobility. Deals multiple hits of flinching damage before launching.
- Down Special - Lunch Break: Agumon will pull out a cartoonishly large chunk of meat on a bone, and begin chowing down, filling his Digivolution Meter slowly. While eating, he can be interrupted by an attack. If he is, the meat will be dropped as a food item, which either player can then pick up to heal a small percentage of health. After the food is knocked away, Agumon will have to wait three seconds before using Lunch Break again.
WarGreymon’s Special Moves:
- Neutral Special - War Driver/Terra Force: When the special button is pressed a single time, WarGreymon will perform an upward slash with his Dramon Destroyer claws, sending waves of fire across the ground. In mid-air, this will instead send a short burst of flame forward from his character model. When the special button is held down he will hold his hands above his head and gather energy into a massive fireball, which he will throw forward when the button is released. At full charge the fireball deals immense damage and knockback, even stronger than Hero’s Kafrizzle. However, unlike most chargeable moves, the charge is immediately lost upon shielding or dodging.
- Side Special - Dramon Destroyer: A lunging claw attack, similar to Agumon’s Mach Jab. However, it deals increased damage and massively increased knockback, launching foes straight forward instead of diagonally upward. It also has super armor, making it one of his best KO options. On the flipside, it also has much more ending lag than Agumon's Mach Jab, making it unsafe on shield.
- Up Special - Brave Tornado: WarGreymon spins rapidly and repeatedly damages any enemy caught in the attack. When used on the ground, he will remain on the ground and can move left or right, similar to Bowser’s up B. When used in the air, however, he will fly upward, and his trajectory can be tightly controlled while flying, similar to the Mii Gunner’s Arm Rocket up special. Unlike Arm Rocket, this attack deals damage on contact for its entire duration.
- Down Special - Brave Shield: WarGreymon uses his shield as a combination counter and reflector, similar to Joker’s Tetrakarn/Makarakarn.
Final Smash - Omnimon/Omnimon Merciful Mode: Agumon/Wargreymon will swipe with his claw in an uppercut motion. A short cutscene will then play, slightly different depending on whether the attack is used by Agumon or WarGreymon. As Agumon, Gabumon will show up in the scene and merge to form Omnimon, followed up by Omnimon slashing with his Transcendant Sword attack. As Wargreymon, all of the fully-evolved partners of the DigiDestined appear, and they merge into Omnimon Merciful Mode, before following with a devastating slash with their Fearsome Blade. Though the attacks are different in appearance, they have no mechanical differences.
For the alternate costumes, I figured that it would be neat to have most of them be references to major digimon from other anime series. In order: Default, Blue (Veemon), Red (Guilmon), Lighter Red w/ White Chest (Agunimon), Slightly Lighter Default w/ Red Armbands (Savers Agumon), Purple (Gumdramon) White (SnowAgumon), and Black (BlackAgumon)