>>47231662Lore-wise, I'd say it shifts forms as it's perceived because it's basically everything that hasn't been created. You could perceive some component parts since not everything about Missingno is unknown in-universe(e.g. it uses moves like water gun and sky attack, has conventional base stats, etc.), which is what the 5 forms are. I think objectively the block form works best(even though there's more than one "block" form between RB and Y) since blocks would probably represent glitches best and be a commonality between the forms in practice, but I personally am a fan of the ghost form. The ghost form is already a lack of perception(no silph scope to perceive Marowak) so that overlaps and it's the only one that could let Missingno speak or emote in a conventional way(e.g. a bunch of different expressions at once from what comprises it). tl;dr technically all of them, but block has the most merit, followed by ghost.
In game terms, the forms could indicate "phases" of the boss fight, sort of like how Eternatus has 3 "phases" in game. Whatever narrative significance Missingno would have could influence the order the forms progress through. I think either starting with ghost and ending with block or vice versa works best, but those sprites probably have an order in RBY's index you could reference.
