Every potential character could have a bunch of different Spirits for their board. But, can they have a legend Spirit? So far, the legends we have are...
- A collection of characters. Ren and Hero brought the Phantom Thieves and Hero's Comrades.
- The main antagonist of that Challenger Pack's game. Banjo and Terry had Gruntilda and Geese Howard.
- Sothis, who is a deity and a very important figure to the lore of 3H, as well as where Divine Pulse comes from. From Byleth's board.
The Zacian and Zamazenta spirits are the only DLC Primary Legends so far, but I'm not going to assume that's a hard and fast rule. But if it is, then a Legend Support Spirit must come with a new ability. So, if the character you wanted got a legend Spirit, who would it be?
Arle, for instance. Regardless of the identity of the Legend Spirit, as a Support they would have the ability "KO Boost", which makes you stronger after every KO.
- Carbuncle, Arle's most iconic companion, and a Puyo powerhouse that is feared by all. Could possibly fit as a Novice as well, but him being a Legend references his status as a superboss and masterclass AI.
- Doppelganger Arle, or more specifically Pierrot, the popular final boss of Puyo Puyo 4. If the normal Doppel is one of Arle's alternate costumes, then her disguise as Pierrot could fit here. Pierrot could, however, also be a Novice that evolves into Doppel, a Legend.
- Puyo Heroines, consisting of Arle, Amitie, Ringo and Ally. The main four characters. I don't usually think of this as a good option, but if all else fails, then this'd work.
Those seem like the leading two candidates for legends. I have other characters who could fit that mold, but I feel like these two have the strongest claim. Satan could be here, but I think an Ace that evolves into a Legend spirit would fit better, or even just a normal Ace spirit fits.
You don't even need to think of what they'd do. As long as you can think of someone or something to fill the Legend Spirit slot, you're golden. For Crash, I'm thinking Cortex is too obvious of a candidate. Instead, it'd be Aku Aku, who'd grant Invincibility Duration Up. For Lloyd, easily Yggdrasil. Frisk, I'm thinking the Annoying Dog as a Joke Spirit (ability: Initial Damage +100%.). When it comes to Paper Mario, it could be the Star Spirits, who would have the ability to nullify stat bonuses to enemies with Spirit boosts (let's call it, Stat Up Seal, or maybe just Star Beam).