Macan should be putting out plenty of damage, so my recommendation is still to find a friend with either Aizen or Snow, and abuse the hell out of their LB3 skill.
Even a non-friend of either of these two will be worth using (as long as they're limit broken as much as possible); you won't get their charge skill, but that's not what you're running them for.
Failing that, another Thunderbird, Eita, Durga, Temujin, and Kyuma all have skills that ignore evasion, or you could use a support that inflicts damage through skills (e.g. Omen from Shino/Chernobog)
If you're getting close to winning with a particular setup, remember that you can restart a battle by closing and reopening the app (and then selecting the option on the left).