The hallucinated character won't be able to interact with the real world, though to the schiz it looks like it does, so other characters won't be able to hear, see, or feel it at all. And even though it looks like it's using attacks to the schizophrenic, it's really having no effect on the enemy. The main thing the hallucination does is talk to the schinz, persuade him on what to say and how to react. So pretty much a non-existing Pokemon is controlling a real one through words.
I thought this would be an interesting idea, and wanted to see if I could actually do it. Also, two tickets will be required, right, even if one Pokemon is simply a hallucination?