Venom (especially eddy) and Carnage are both some of my favorite characters but other than carnage possessing them (that kinda seems a kinda cheap like a BFR or something) I don't see them being able to hurt colossus or thing all that much. They may be able to drown thing with their tendrils but colossus doesn't need to breathe while in armored form. Both Colossus and Thing are strong enough to thunder clap which should effect the symbiote quite a bit. In a straight up fight two class 100 bruisers with great fighting skills should be able to take venom and carnage who are both around 50 tonners. Especially where carnages main attacks are piercing attacks and blunt force and venom is usually a brawler style fighter too. Ill give it to the Bricks 9/10 if possession is not allowed.