2v2 1k points ea player 4k points total.

[Fallen Avenger]

So between myself, 2 of my cousins, and one of their friends were having a 1 k ea doubles match.

 

the forces will be Grey Knights, and Dark Angels with Assassins Vs Thousand Sons and Emperors Children. 

 

I will be able to find out what GK's ill team with but dont have a clue about the 1k sons, can anyone give me some pointers on what to expect from the 2 chaos armys more specificaly 1k sons.

[Paladin777]

Well, at that point level you will probably see 1 maybe 2 squads of rubric marines with their AP-2 bolters, probably 1-2 squads of Tzaangors which are fairly quick, cheap, and effective close combat fodder. For HQ you will probably s e Ahriman as he is really good at what he does for his points. He might have 1-2 tanks or 'dinobots' for anti-tank as well.

[Fallen Avenger]

Well, at that point level you will probably see 1 maybe 2 squads of rubric marines with their AP-2 bolters, probably 1-2 squads of Tzaangors which are fairly quick, cheap, and effective close combat fodder. For HQ you will probably s e Ahriman as he is really good at what he does for his points. He might have 1-2 tanks or 'dinobots' for anti-tank as well.

what are their weakness's? 

[Grendaxe]

Short rundown on the TS options:

Magnus
Warptimes himself to the front. If you have 1 deny, use it on this power to give yourself more time to shoot him down.
Has super smite that can deal 2D6 mortal wounds. Keep low cost infantry in front to eat this. While the smite is potent, his CC is scarier for high wound models without invul saves such as tanks/flyers etc. (8 attacks, WS2+ reroll 1, str16, 3D fixed)

 

Rubric marines/Scarab occult
Quiet some s4 AP-2 shots. Infantry killers but useless against anything T5/T6 (soulreaper upgrade is +1s/-1AP extra. Still only good versus infrantry)

Try to hit them with D3 or 2 Damage type weapons on them to remove the +1 save. Overcharging plasma is very good if you got a reroll 1 aura nearby.

Tzaangors
Good cheap chaff with T4 and a 5++ with decent CC abilities. Gun them down with bolters. The 5++ saves will not save them against volume fire.

Exalted Sorc
Nothing special about these. Just regular psykers. Deal with them like any other psyker you normally would.

Ahriman
Upgraded Psyker. Decent unit with 3 powers and +1 to cast. Deal with him like any other psyker.

[Raven1]

with the exception of Magnus or options of fast close combat units or anti-tank are limited. TS excel at two things (generally) volume of S4 AP-2 and smite spam.