But yeah, I do like keeping it simple more than for example Ho-Oh or legendary birds from Gen I being shown in it although all of them can be caught in the game. Those just wouldn't make any sense for being there. I think that if there is no particular reason for an add-on (whatever the add-on is), there is no point in having the add-on either. If you include some kind of theater in your hack just because you feel like adding a theater in one town, what's the point. You could instead use a bit more imagination and make the theater having an actual purpose for being there; make a storyline related event or side-quest happen there or something.
Anyway... yeah, having "PRESS START" type of dialogue in it would be a good idea (at least it wouldn't hurt).