I won my first 5 GW's in a row and then lost a bunch after starting the final node or just before. Yesterday and today I won GW. The leader ability makes a huge difference. I usually start with bariss in the lead but by the second last fight today I had two characters die before I could attack. I retreated and I switched so chewie was in lead and it changed the computers pattern giving me enough edge to win the match with all 5 characters and at full health based on timing my heals. Switch the leader around if you're stuck. As one option. Even helps when fighting teams much higher levelled and geared than mine. I usually focus all special attacks on one main attacker and heal a lot until that character is gone. Rinse and repeat.