>>35901378I'd keep Palkia's general shape the same but make its armor with something like pic related in mind, basically using sheets of a metallic looking substance (not grey) as a stand-in for the concept of space. You could have big flat sections, intersecting planes, really tightly warped parts, etc, all to suggest what Palkia can do to space. I think it'd also be cool if parts of this stuff had runes inscribed into them (maybe Unown runes) that no one really knew the origin of (man-made or Arceus-made?)
Extending this metaphor, you could put something similar on Dialga, but more cylindrical/wirey instead of sheets to suggest the one-dimensionality of time. Maybe you'd incorporate branching structures, winding structures, circular bits, etc if you wanted to posit certain philosophical ideas of what time really is. Both of these would be done with some sense of coherence/order (different than simplicity), so Giratina's would be the opposite. Not sure how that would word exactly, but that's the idea I'd run with.