Hey there. Just played a game with my Imperial Guard against Space Marines. They are the splinter in my heel. Every time I play them I find them ridiculously hard to beat.
My guys are just so weak against them & those 3+ armour saves never seem to fail!
In my dismay I believe that I have finally found a list that makes them at least tip-toe about me slightly, if not actually fear the might of my fire power & seek cover at every opportunity.
The list is as follows.
HQ
Company Command
Plasma Pistol
Plasma guns X4
Chimera - Free Flamer
Troops
Veterans
Meltas X3
Heavy Bolter
Chimera - Free Flamer
Veterans
Meltas X3
Heavy Bolter
Chimera - Free Flamer
Veterans
Meltas X3
Heavy Bolter
Chimera - Free Flamer
Hellhound - Multimelta
Hellhound - Multimelta
Demolisher
Demolisher
Vanquisher - Pask
1495
I hope that you guys like it.
I have found that using Squads of Vehicles is really quite a hindrance rather than a bonus.
The bonus - you can get more Tanks in a list. The hindrance - The Tanks are destroyed much more easily.
That is why I am not running any Vehicle squads.
I think the above list will definitely give any opponent something to think about.
Plenty of Tank busting units, ranged & close to deal with Mech Armies.
And plenty of flamers with a few pie plates for horde/swarm/infantry armies.
All comments welcome. Please keep it friendly though.

Cheers.