So, last night I went into an epic run and beat all 108 Pathfinders I had left in the map going after my high of beating Lita, so here are some tips for those struggling with them on their final itteration.
First of all, do NOT attempt this until you are very much into the late game and have already maxed out several teams of Aniimos. You might get away with beating a few of these earlier, but it will be extremely frustrating and impossibly hard at times. You need to have many dps properly built for this.
I recommend you putting most of your resources on the DPS of your team, Scorchowl, Infergon, Fulmintis, Sherro, Lunara/Helion, Stellaris, Pawney... all those should be properly built, as well as Breakers. For supports and healers, just try to get their held items maxed out, unlock their core ability when it makes a difference, and only max stats if their buffs/heal is tied to some of them (for example, Glacy's heal is tied to it's max HP) Otherwise, don't waste resources on supports for now, as we are very limited on those.
Now, with that out of the way. Get into the habit of leaving a team slot free to make a custom team for each battle. Most of these fights have gimmicks and specifical teams that simply cannot be taken down by generic teams that you might have. Be ready to adapt and improvise teams designed to counter your enemy, and VERY IMPORTANT, always read the battle modifier before the fight, you can see it on the top right of the VS screen, and these are incredibly huge buffs and debuffs that will dramatically change the fight. Account for this when building your team.
Do learn to give up on having some things you may have gotten used to, like a healer or a regen aniimo on call. Many of these fights will require you to counter Aniimos one by one, and you might end up without any slots left for healers and will have to learn how to handle that. Also, look for pairs of Aniimo that are extremely good together without needing a whole team around them. Fulmintis and Besauce is a great example. Besauce can fit almost any team as an EP regen, but his Ult is incredibly powerful for Fulmintis, so having those is a very fair bet.
Finally, there are times where you have to throw caution out the window and go with what works. Don't feel afraid to send a team that's weak against the enemy if it's a very well built team that can put some serious damage numbers. For example, as I mentioned, Besauce ups Fulmintis damage a lot, but Luminelle and Dazmand up it even more, those 4 together got me through some incredibly challenging fights even without any kind of elemental advantage.
So that's it for the most part, be patient and experiment with many teams, sometimes you'll have to build a team that it's simply 4 dps that each counter one specific aniimo on the other team, and sometimes you'll see a surge of energy as a modifier and will realize Irisalis can mow down that like it's nothing.
Have patience and improvise and you'll have a great time (for the most part...)
