Dragons? What?
SPOOOOOOILEEEER AAAALEEEERRT
Not sure if serious but you can see the Dragons as early as maybe an hour into the game :x
What is the best endgame setup?
I/B I/B with some assortment of the rest of the buffs (Dancer, Medic) and debuffs (Arcanist, Runemaster, Sniper) is the most likely candidate for "best" party in terms of raw damage output.
I'm hesitant to really say there's anything that can really be called "best." Links just fall out of favor a bit compared to "turn 2, I deal all of the damages" setups.
Or, basically, Imperials do a metric fuckton of damage and you can just plan around ending fights before you deal with their cooldown period.
Edit: Just to note though, Links are still amazing in the end-game. There's just faster setups as well. There's a lot of viable options, really. Anything short of "We just defend a lot and then hooray win!" is probably able to find a way to victory.