2000pts vs Ultramarines/Imperial Guard

Hi guys, so match number 2 and I'm plaing the most WAAC (win at all costs) 40k player at the club: he asked me specifically "Do I tailor lists to fight vs specific enemies?" I said no, and he asked me if I only play DE in 40k, to which I replied "Yes." Since then I have found out that he is using Allies but is not revealing WHO his MAIN FORCE is and WHO his ALLIES are. I suspect that it is Ultamarines (main force) and Imp Guard (Allies) but I can't be certain!

What I do know is:
- he knows I play exclusively DE in 40k
- he has beaten them in the past a LOT
- he collects Ultramarines (mostly) and Imp Guard (his other army)
- he plays to win / is competitive

With that in mind (and the fact that we are playing 2000pts) has anyone got any help/hints/tips. I am determined to win as he was bragging how easy the game would be: for my pride and the sake of our race (and Xenos in general) I REALLY want to kick his arse...

edit: this was written very late last night and involved a lot of vodka so apologies for the scrawlings... I'm going to post a reply soon with my actual list that I am considering: this is afterall an army list thread

if he is a WAAC player, he will most likely have vulkan w/ some TH/SS termies in a LRC. Some lasplas razorbacks or melta bunkers (10 man MM, M, Combi M in a rhino) and Riflemen dread or two (maybe drop pod dread... Vulkan really helps that single melta) and his allies will either be a CCS, a Vet squad in chimera and hydras, or a CCs, Vet squad in a vendetta.

Pretty much that is what you have to face. Your best bet is to do what we always do... Shoot everything full of dark matter and poison. Once you post your list I will critique it, but until then... GL

that person is like me pal, asks as if this was natural stuff and if you ask back: you'll find out soon enough. That person isnt a WAAC, thats simply an ars - forgive me, but he is x)
All in all, i would advise a hybrid list, containing wyches, warriors, incubi, true born, VRB, RWJF and Ravager.
Perhaps 2 wyches with a haem each, 1 incus with archon and a haem, blasterborn and cannon born, and aprox 8 missiles for tha flyers.