Without knowing what limitations you'll have to deal with or what kind of armies you'll be facing, it is difficult to give advice. There's a few general things you can think about which might help.
If your teammate is going to use mainly wraith units he probably won't be bringing many bodies to the battle, which could hurt you as a dark eldar player as there will be less target saturation for the enemy. Venom spam might help you here, creating more little frustrations for the enemy
of course they bring many splinter cannons and you can put kabalite warriors in them. A blaster in each squad would be good here which leads me to the next point...
If you focus on anti-infantry, can you rely on your teammate to bring sufficient anti-tank for a 2000 point game? Athough they aren't kabalite, reavers can shine for you here as they are very capable of doing both. If you find you are struggling to bring enough anti-tank then maybe a small trueborn squad with two dark lances might be worth taking as they don't cost a lot of points. I have used this squad a few times and struggle to keep them alive before doing anything productive, even if deployed in cover. So you can try it but I wouldn't personally recommend it
I find the extra points for a ravager is always a more sound investment.
This probably doesn't need saying but you should definitely talk to your teammate about what you're both taking, discuss tactics etc and maybe have a few games before the tournament to get to grips with your 2000 point team. You don't want craftworlders ruining your evil plans or somehow limiting your own manoeuvrability. Make sure your teammate understands pain tokens, if there's an easy kill going, it's wasted if the craftworlders take it.
That's about all I can think of right now, hope it has helped in some way.