>>48456178HC's theory is that the index order is separated by periods as opposed to designers just copying their shit over. There's actually more blocks that separate these events than HC leads on to believe.
There's also six unique styles as far as I can tell, they're actually easy to discern:
- Early Sugi: The Kaijuu, follow SD Ultraman figure poses
- Late Sugi: follow sprites closer to the final artwork
- Morimoto: comedic mons, typically mirrored or disproportionate, his initial sprites also were very big and had to be rescaled later on (Poliwag, Venonat)
- Nishida: cute mons, typically feature heavy amounts of antialias from scaling down from either Corel or Photoshop (they were both available at the time) and then got "elemental particles" drawn on top for typing. They also have consistent sizing for the lines (40x40, 48x48, 56x56)
- Unknown 1: Very "anime-like" shading and super clean lines like seen with Persian and Aerodactyl
- Unknown 2: Very "clay-like: shading as seen with Machop, Abra, Golduck
- Fujiwara: Eevee, Jolteon, Flareon.
There's also some swapping here and there for Venusaur/Ivysaur, Shellder/Cloyster which when fixed, helps you see the blocks more clearly.