Pokemon has a lot more potential than Harvest Moon.
You can script Pokemon battles, perhaps. The only thing that may fit into Harvest Moon to add this "excitement" and, you know, gameplay goal would be cruel, sadistic cock fights or something. I don't think that'd run well.
What's in Harvest Moon? Farming? That's in Pokemon, too - berries and apricots.
Mining? Already done in Pearl/Diamond/Platinum.
Fishing? Pokemon did it, 1996.
Marriage wouldn't really fit, but that's what breeding is for - perhaps a complicated script, though, but possible if you're really into it.
Pokemon I wouldn't mind. The fanbase for Pokemon is ridiculously high compared to Harvest Moon - that's why the games come out soon after Japanese releases (<6 months), while Harvest Moon games take two years to translate and release.