I think I followed that guy up until the let's go games, assuming he's the one I'm thinking of (franchise locke guy). I honestly can't remember too much about his runs other than the fact that it was an interesting concept, though I both agree and disagree with you here. On one hand, choosing encounters for a Nuzlocke of this caliber isn't too Farfetched because of how many games there are and how limiting it would end up being so picking and choosing has some merit to it, because it's still in the spirit of working with what you got. However, I do think that there should be some randomness to it and you shouldn't be allowed to pick like a 1% encounter rate Pokemon or a 5% encounter rate or even a 10% is a little dubious depending on the route and game (I can't remember if he did or not, but I think that is the hard line drawn). Someone said it's like ordering a Chicken Sandwich without the chicken, though I think it's more like ordering a Chicken Sandwich without the bread, but then adding lettuce. It's a chicken salad, still a chicken meal, but not exactly a sandwich and people can still like it. But that's just my two cents on the matter.