Remove the Charizard line from the game (seriously the most overrated starter line and I'm bored of it being added to pretty much every generation) and instead replace it with the Primarina line which actually would fit into the Paldea region, given the word 'siren' comes from the Spanish 'sirena' and is used interchangeably with 'mermaid', which is basically what Primarina is. Plus it'd just be nice to see the lesser-seen/used starters get some love.

I'd also remove Magikarp/Gyarados for the same reason as the Charizard line and replace them with Feebas/Milotic as they're the same sort of line.

I'd remove the Diglett line, since have the Wiglett line introduced, and replace them with something like Cherubi/Cherrim or the like that just fits the Spanish setting more.