You make it sound like Spidey people don't deal with gas attacks every other day. They know exactly what to do in case of gas. They would be moving so fast they could either...1. Just run through it. 2. Just stop and avoid it. 3. Jump to another angle and attack that way. 4. The list goes on.
Spidey Team has too much going for them. What's to stop Spidey or one of the others from webbing Batman's hand while he's holding a grenade or smoke bomb? It would be stuck to his hand and there wouldn't be anything he could do about it.
You make it sound as if Team Spider just rambles on into battles, like Juggernaut. Even if they charge, they're still ready and fully prepared for anything, and be able to dodge anything as well. Even though Spidey usually fight alone, he has very good knowledge on how to lead a team, since well, he's done it before several times. He knows how to be led as well, though that won't be the case in this match.
And don't forget the webbing. If one person is webbed up in a way that they are incapacitated, that's one person out of the fight, since the webbing lasts for several hours.
There's just really nothing that Team Bat can really do to Team Spider to really hinder them in the slightest. I mean, if you think about it, Robin and Batgirl will probably go down first. And then that leaves Batman and Nightwing. 2 on 1 for each one. And then Nightwing probably goes down next. Four Spidey people on Batman. That's most likely what will end up happening.