>>48161772rule 2 is the soul of nuzlocke. If you're an advanced player you likely plan your team out every playthrough and keep resetting or catching mons until you get favourable stats/natures. In a nuzlocke that preparedness is thrown out the window and you're forced to use a team you never would. It's also fun to see what pokemon you get each route and use pokemon you never normally do
The random team makes the challenge more difficult since you most likely get shitmons with meh stats and natures. For advanced players (i.e. adults) it makes pokemon exciting again, while rule 1 makes it nerve-wrecking and forces you to strategise when facing tough trainers. Nuzlocke makes this children's game engaging again