I just rewatched Arceus and the Jewel of life.
It's WAY better movie than I remembered and actually gives tons of small tidbits of pokemon past lore.
It had very interesting aspects that I noticed are repeated over and over in many pokemon media since then, and none of the movie lore actually contradicts with anything released so far.

>Pokemon can fell for "rage", and this makes them dangerous and unpredictable. This rage can affect ANY Pokemon, even Arceus can fell for it.And this is probably the rage that shadow pokemon technology used and rage that Giratina used to make Alpha pokemon mad in PLA.
>Pokemon were seen as weapons and forced to work and battle instead of being treated as equeal partners in the past
Love this aspect, as it's actually very logical. People afraid of pokemon so they want to controll them imidiatelly, and best way to do that is by force.
>They show main semigod trio as more animalistic than normal Pokemon(aspect I actually love in media), but they still can connect with/bond to humans as any other pokemon.]
They have own problems, can get mad at own sibling just to calm down and work toghether. LOVE IT.
>Without plates Arceus is weak
This annoyed me as a kid but now I apreciate it way more. A GOD that is not omnipowerfull? That can be drown in silver/mercury? LAME! But today flawed gods conceept is much more fun to me, and Arceus with its type plates is very solid concept of a "leader" creature.
Interesingly fact that Arceus is not as strong it seems to be shown in other medias as well. Even in maingame Arceus itself is not very good pokemon, because he cant controll all plates at once (which is a shame), and in Conquest you only unlock its ability Multitype if you collect all plates.

So here I open a thread for Pokemon Lore I guess. Let's hope S/V will show us more of pokemon past!