Need help modding GAC defence teams in the future!

You seem to be under the (wrong) assumption that all characters on defense need to have mods with defensive stats. That's incorrect. Attackers still benefit from offensive stats, key characters that need to possibly out speed your opponent still benefit from speed, characters that have abilities that trigger from crit chance still benefit from CC etc. even when on defense.

If you want more specific advice please post a link to your roster.

I think you should focus on speed set mods

High defense stat =/= defensive wins in GAC

This is a turn based game, and the faster your toons, the harder it is for your opponents to beat your GAC defense

You mod your defensive teams regularly, not with defense mods. In general you farm mods from the set of the stat that you want most on that character, then get primary and secondary stats that benefit you.

Let’s use Grand Master Yoda (GMY) as an example. Because he gains so much turn meter, it is often better to mod for damage output rather than speed. Give him an offense set with as many offensive primary stats as possible. For your secondary stats, make sure to still have some speed and some offense, but potency and health won’t hurt. Because speed set mods requires four for a set, you have to pick another set for the last two mods. Crit Chance, Health, and Potency are all fine. Use the same primary and secondary stats as above.

Ask you guild mates (or the forums if they don’t know) what stats a character benefits from most, and then farm the mods in order to get the most of that stat.

There are lots of modding guides out there, but keep in mind that they provide general advice for a character, and there may be a better way to mod that character depending on the team you use them in and that some guides may be outdated.