I'm trying to plot reset for Tom but he refuses to move into the spot I want. I don't want to spend all day resetting if the spot isn't even viable. Is the nearby pond preventing him from moving in?
I have someone living quite close to a pond (with a corner not the whole side of the house) and I can't imagine that should be an issue. The question here is if he moves to other spots because you missed a pattern and left enough space open by accident... If that's not the case then the game is avoiding the path rule because there is no other option. At least I have read before that houses will be set on paths if there is no space elsewhere and based on the little experience I have with plot resetting: if a space is valid and you didn't leave other open areas, any house will appear there and only there.
My suggestion is make another space at a place where you KNOW all rules are met. If he allways moves there instead of the spot you originally picked, you know for sure that the game won't let him.
I have 2 villager houses one space near the river (probably same rule with ponds) so I don't think that's the reason. Maybe you somehow reached the acre limit in a given area? or you can try closing other possible 3x3 spots with patterns if you have more than one then see if he'll plot there
I don't think villagers will move on top of paths if there are no other spots availabe: a few days ago, I asked Elvis to move in from the campsite. I filled my town with paths so that there was only one spot he could move into, but the next day, he didn't move in anywhere in town. I think he didn't move in because the spot I had chosen was near three other houses, or maybe because it was too close to a cliff. I then cleared some more spaces of paths and waited until the next day. Sure enough, he moved in to one of the new open spaces. I don't have a lot of experience moving in villagers from the campsite, so maybe having a day or so delay between when you ask them to come and when they actually put down their plot is normal, but if it's not normal, than I don't think it's possible for villagers to move on top of paths.
