After recently unlocking Cody and Rex with only Echo to go, I'm planning on going for a Cody lead for his leader ability when they are all 7* but I'm stuck for what mods I should put on who
Mainly health mods. But increase the stats which are strongest for them. Echo is squishy so health mods. Red and Cody could be good with two 5* offense mods and the rest health. Fives definitely needs health as he's the only tank. Best one you want to do is JKA as lead or Rex. Mainly because Cody has an ability to call in assists anyway.
i run a clones team and a lot of the above is good advice. I run Rex with higher protection over speed though. Once you get to the top tiers the meta speed from wedge is going to beta what rex can put up with and you need him to survive the first onslaught to give out SD.
One thing with clone sarge is you MUST put a Critical Damage primary mod on him. With cody lead I have him at around a 90% crit rating and I have him with all health mods.