Roleplaying is not banned anymore in general. However, certain threads may have their own custom rules regarding different things. It seems to me that this thread prohibits roleplaying not because of wiki rules, but because the thread creator wants it that way.
To make a disambiguation page there must be at least 3 pages for that name (excluding galleries). Not sure about the others, but I'm pretty sure that Bombegranate and Shadow-shroom don't meet those requirements.
The same requirement applies to recurring characters, so yes, you can make the pages for Bamboo Shoot and Rafflesia.