>>19872132BW2 is pretty good, while you can do a Nuzlocke it is generally one of the harder games to start one in due how the early game plays out.
If you can cheat or link with someone who completed Black 2 i would recommend the challenge mode and play normally on that.
Since you skipped BW1 you have plenty of Pokémon you should catch in order to transfer to XY too, meaning a Nuzlocke may be a bit harsh if you (un)luck out and get one of those fucking 1.25% chance encounters.
There is also in game features that explicitly tell you when you caught everything in an area, making this BW2 the easiest to "Catch Em All" in as you go.
So i'd recommend to run with that as goal and then transfer everything you get in it with you Gen III and IV Pokémon.
