I'm replying here because the thread is locked, and it's a mess of ideas anyway. The LGPE Pokedex entries are from Yellow. I am not sure why you implied that recent and old entries are both of lesser value, though. I think that the old ones count more, and restating them is a bit redundant. Articuno can control ice, snow and blizzards (surely associated with winter only). Moltres brings early spring (Silver, DPPt). Zapdos only has one entry to go on, but thunderstorms are most likely to occur in summer (especially in Japan, where they're rare otherwise). The discussion started with Articuno and Moltres, though. The movie shows how the birds can disrupt the weather (snow during the summer). I wouldn't compare Sea Spirit's Den to that Alain reference. Lugia exists in-game while Alain doesn't, after all. I'll agree that Let's Go Johto is their last chance to actually make a connection. I am not saying that they're necessarily vital to the seasonal cycle. It's enough that they're tied to their respective seasons and weather therein, and I wouldn't want them to be usurped by Groudon-tier legendaries especially as it would probably lead to an RSE-like plot. Speaking of Solgaleo and Lunala, do they really have a connection to the sun and moon? Do they just store light?