i remember i wanted a spore character which has even less chance of ever happening. i recall in may 2019 i made a basic moveset for one and i posted it on a discord and this guy told me that nobody cares for some godforsaken reason and i was literally so upset over this i was completely embarrased of this whole moveset i made ever since
The way I see it, Spore characters absolutely have to be some pre-created Maxis creature from the game or a creature originally designed for Smash Bros. They'd all share the same body type (most likely being a biped), but alternate costumes with be them using different Spore parts (such as one costume using beaks, other using carnivorous mouths, others using insect mouths, different eyes, different details some outfitted with city/tribe/space stage parts, others all natural), different voices and different colors as well. Depending on their moveset, they might have wings of different types as well, if their wings are used for attacks or for their Up Special. Bike, Strike, and Charge would be their normal moves. Spit would be a special move, and the socializing parts could be specials as well. Their consequence abilities such as Raging Roar or something could be final smashes, or just summon the Sea Monster to eat your opponents or a UFO to abduct opponents. If you want, they can also take liberties and use tribal weapons as well, such as spears, axes, torches, and the odd fruit staff.
There's no way they're going to implement something as complicated as a Creature Editor in the game should a Spore fighter become DLC so that's likely not going to happen so there will be preset archetypes.
Spore also has various spin-offs to inspire moves from, namely Spore Heroes and Spore Hero Arena, so it doesn't entirely have to be all mainline games. Spore Hero Arena does have kickass fighting music though so that should absolutely be used for stage music.
A Spore creature can additionally be designed after Galactic Adventures too rather than base Creature parts. Warrior, Shaman, and Scientist parts are enough to make a full moveset and you can throw in Bard/Diplomat parts for taunts or even part of the attacking moveset if you like.
Spore can also be repped by something like the Grox as well, who can have a Grox-themed moveset as they're military powerhouses and can make up moves for them and their cybernetic implants as well as vehicles from the Galactic Adventures portion of the game.