although perhaps I'll add a thing where the Reincarnations can only use Pokémon corresponding with the typing their Legendary is. For example, a Palkia-Reincarnation would only use Water and/or Dragon Pokémon.
A series of monotype (or duotype) teams would feel restrictive, yes.
Also, I'll probably allow more than a single Pokémon as the starting teams, but give them a limit, like 3 Non-evolved Pokémon or 2 Non-evolved and 1 evolution Pokémon that evolved once.
If anything, I recommend limitations based on base stat totals, since pokemon like Scyther and Pikachu throw evolution as a balance metric out the window. (Scyther being too strong and Pikachu being pretty weak, but Pikachu is the evolved one) I'd ballpark it at 401 BST and under (the only 401 BST pokemon is Archen, who has a negative ability) Fully evolved shouldn't be a problem either under this system. (Kricketune isn't gonna hurt anyone) It includes a fair bit of evolved pokemon (Graveler, Gloom, Beautifly, Kadabra, etc.) but any lower and you'll exclude pokemon like Roselia, Wailmer, Porygon, Munchlax or Onix. This would exclude 2nd-stage starter pokemon. (most of them are base 405) It would also exclude pokemon like Plusle, Minun, Pachirisu, Murkrow, or Ponyta, but I figured starters were the best metric on where to draw the line.
Alternatively, you could give a bst budget and restrict evolutions altogether. No need to balance Scyther and Pichu when you can have twice as many Pichus.
I feel like you have a point when it comes to themes being influenced by the Legendary's background rather than typing. For instance, the person who would get Darkrai could have a lot of sleeping/dreaming-based Pokémon, which could also be Psychic types or even a Snorlax.
I don't know about that. I was thinking of going loose with themes so that they could exemplify the character's own tastes and personality. While they would, to an extent, embody the pokemon they are reincarnated as, it doesn't necessarily mean that they would like pokemon that are similar to it. For example, if there was a Giratina reincarnation, maybe they wouldn't like ghost types because they don't like/are bored of the reverse world, and would prefer to seek out pokemon that are exotic by its standards, like a grass type as a Persephone to Giratina's Hades.
Meanwhile, how does everyone think about having a Discord server? I'm gonna make the OOC later tonight but I can perhaps whip up a quick Discord.
Sounds convenient.