As for the pokémon pool or range for the quest, I think they are pokémon that can be found in Sinnoh region. Meaning it should be starting with dex number #387 (Turtwig) and onwards. Well, that's just my assumption. Once we have more information, I can add the list later.
As for the progress reset, when you started again from day 1, you received the same rewards? what about your day 4 rewards?