Steelix-I'd suggest giving him the ability sturdy rather than Sheer force, that way he can set up the rocks no matter what happens. You might even consider giving him a Red card to force a switch if something is able to counter you well for the hit. Leftovers can do the job if the hit won't be a OHKO. You could also look into a spinner since you have charizard on this team.
Kingdra-I'd suggest surf over Hydro pump just for reliabilities sake. Draco meteor will pretty much wreck his special sweeping abilities, and I'd suggest only using it if you think the opponent will try to switch in on a counter. You don't need two dragon type moves for that matter. You won't be able to cover very much in terms of typing.
Metagross-I'd suggest Earthquake over Bulldoze. I understand where you're trying to go with the speed drop, but competitively, most people will just switch out anyway, and be able to take him down before he can make the drops effective enough.
Charizard= I'd suggest against dig here. Two turn moves means your opponent can easily switch in on something to get an immunity on it. I'd suggest doing with a substitute or even a sub-belly set if you're gonna go for a physical set. Aerial Ace might get STAB, but it's still not gonna be that powerful on him, and like I said earlier, I'd highly suggest using a rapid spinner on your team to help him out. You also don't really need two fire type moves. Dragon dance is also another idea to help him sweep.
Galvantula -He seems pretty good for the team.
venusaur-I'd suggest dropping Leaf storm and giving him Synthesis for quick recovery when you need it. sludge bomb might be good for a poison chance, but I'd suggest going for toxic. Since the sleep clause will only let you use sleep powder once (followed by a switch) having two status moves would be okay in this case. Leftovers can give health continually, and doesn't depend on your using giga drain to work.