I'm sure Walking Wake and Iron Leaves will be made available again, their Pokedex entries in Pokemon Home just say "Ecology Under Analysis", which to me sounds like a placeholder. It could be another Tera event, or they could have a role in the DLC's story, either way we definitely haven't seen the last of these two.
I've started a new Scarlet playthrough, choosing Sprigatito as my starter again. I'm up to the front gates of Mezagoza and have my usual temporary early game team of Pawmi, Lechonk, Fletchling and Wooper. For this playthrough I'm going to use a Hisuian Zorua I received in a trade as one of my main team members, but I'll only add it after maybe the third gym because of how quickly traded Pokemon level up. My other planned main team members are Tinkaton, Mudsdale, Armarouge and Palafin, I will have to ask someone on here for help evolving Finizen once it gets to the right level, but I'll cross that bridge when I come to it.