I must admit, the Pokenchi preview did suggest the possibility of a capture.
However, there has been literally nothing else hinting at Passimian being caught. No merchandise, no major hints in the opening, nothing. And while I know Steenee and Charjabug happened with very little hints as well, I would think a team change for Ash would be a bigger deal than Mallow or Sophocles.
Unless alolan Andrew and greninja who had been in the march merchandise hopefully we get episodes involving thwm