How dose group attack work

How do group attacks work if someone has a hell of a lot more stats that the people attacking 

You'll probably still lose. Group attack is just attacking someone at the same time as your faction mates. You still use 25e and if they're stronger than you or your mates you'll still lose.

I honestly thought group attack meant the people who join don't lose e, smh.

Reducing an opponent's suppression

Every additional person who has made an action against the victim within 60 seconds will only halve the victim's defensive stats: Defense and Dexterity. Strength and Speed are unaffected. This will quickly remove their dexterity with every additional attacker allowing them to be successfully hit, and penetrate their defense in order to cause damage.

Two attackers: Defense & Dexterity reduced by 50.0%
Three attackers: Defense & Dexterity reduced by 75.0%
Four attackers: Defense & Dexterity reduced by 87.5%
Five attackers: Defense & Dexterity reduced by 93.7%
Six attackers: Defense & Dexterity reduced by 96.9%
E.t.c.


Reducing an opponent's aggression

The victim's ability to respond during turns depends on the amount of people who have made actions against them in the last 60 seconds. With just two attackers, the victim's ability to respond is cut in half, with several attackers their response rate will be rapidly reduced.

Two attackers: 1 in 2 (50%) chance.
Three attackers: 1 in 3 (33.3%) chance.
Four attackers: 1 in 4 (25.0%) chance.
Five attackers: 1 in 5 (20.0% chance.
Six attackers: 1 in 6 (16.6%) chance.
E.t.c.

Source: https://www.torn.com/forums.php#/p=threads&f=1&t=16011774&b=0&a=0