The reason the Shuffle Guardians are purple instead of blue (like Shu and his friends) or hot-pink (Nene) is because purple is inbetween blue and pink in terms of colour mixing but also symbolizes that they're neutral shadows compared to the others seen before or since.
During Awakened Shadow's post-game, you can access New World. The primeval theme seems arbitrary until you realise that New World is based on our planet, which started out in a primordial state.
Considering that most of Blizzard Cube's enemies are clones of the Demon King Robots, it'd make sense that you don't fight them. Instead, the boss can be considered a twist on Ultimate Szabo, with Destroy replacing Szabo.
The reason why the Destroy you raised ends up being one of the game's superbosses? You raised him well enough by feeding him seeds that would ensure his growth that he thanks you for it before fighting you. This is in stark contrast to the Destroy in the first game whose likely been out of practice due to being weakened for years or the Destroy clones in the sequels who never had the chance to express their full potential due to being nothing more than attack dogs for the main antagonists.
Okay, so there's a factory in Baroy Town, which creates Servant Mecha Robos. When the Servant Mecha Robos get summoned to capture the party (or rather, force them to lower the barrier, because Yasato would die if they didn't), they keep coming if Jiro doesn't lower the barrier (the other type of Mecha Robo stops trying to capture the party). How can Nene have that many Servant Mecha Robos...?
During Awakened Shadow, you find an infant Destroy and can make it grow by feeding it seeds throughout the game. However, during the main story, Szabo kills a bunch of Destroy clones during your trip to the Blizzard Cube. Maybe it's for the best that Szabo doesn't find out about the Destroy hidden in Fushira's basement.
Awakened Shadow implies during the Destroy boss fight that he remembers having the power to destroy the Ancient's civilization and offers to show it to you firsthand. If that's the case, then it's clear an army of those Destroy clones would've been enough to raze the world, with one being powerful enough that merging with the Mighty Quartet in it's infant state was enough to fuse them into a Mechanical Abomination.
What exactly did Arcane Dragon do to get sealed away behind the Extreme Door? Considering that it's referred to as "Ultimate Darkness" or "ultimate misfortune" and that it's an Evil Counterpart to the player's shadows (by being a blue dragon that can use similar abilities), perhaps it was sealed away for going rogue aeons ago?
