Territory War advice needed.

I would recommend against defence / attack roles. The defence only players are setting and forgetting, whilst the attack players will have to invest much more time and effort for the same rewards, which will not be good for guild morale long term. 

Usually the biggest hurdle to overcome is engagement. If you’ve got a handful of players that sign up but need chased to set any defences and either never attack or just show up in the last hour and blow their whole roster in one go, that’s what’s failing the guild. 

In most high-end guilds, TW signup is optional and people should only be signing up if they are in a position to log in several times during attack phase to clear a zone. 

As for zone setup, most high end guilds have very homogeneous zones, with all or almost all teams in the zone being identical. The reason for this is to try to make sure your opponent needs all their members signing in to attack and clear your zones. Some teams have very few counters that aren’t complete overkill. 

Tw is always situational and dependent on your/opp guild rosters. You on discord? I can't share what my guild places, but I can share our overall process for evaluating our opps and setting our defenses. We have a few ways of doing it, but I agree with the other reply, having certain people only place defense and actively choose not to attack is a detriment. If you on discord and want to chat lemme know. I have calls all the time with guildies from both guilds in our alliance where I help w roster farms and goal setting. 

Apart from what DarjeloSalas already said: Mods, Mods, Mods

Toons and gear levels are identical for everyone. The only difference you can make is mods, and team comp(osition).

Well, that and learning off-meta counters. Don't just throw a GL at a GL, try to use that "cheap" counter that  leaves you with a GL for another hard team or a new release that no one knows how to counter yet.