The sponges merging? Well, I’ve always interpreted that in two different ways: it could be explained off as D4C’s “first” ability. D4C was able to merge different dimensions together, effectively making two or more different dimensions exist coincidentally. The sponges could be seen as “dimensions”, and them phasing into each other would be them “merging” together. If you’re still confused, I’m referring to the part where Valentine first shows off his ability in that park. Wekapipo and Diego both witness different scenes play out. Valentine was able to merge two universes together, but only so that Diego and Wekapipo saw them. At the end, when they tried to shoot whomever it was that was pursuing them, it was revealed to be Johnny Joestar. Johnny was in the base universe, but the other two were being shown other realities - Valentine deceives them in a way that ultimately ends with them shooting Johnny.
