I'm ditching everything non-essential to hold onto some Garps for the next level up event. Don't care about farming Zephyr, I just want a MAX Garp to go with my MAX Bon Clay, to have a general-purpose speedy PSY team.
Mihawk/Mihawk, V2 Helmeppo, Vista, Mr. 3 and Kaku is working decent enough for me. Started with Alvida and Smoker, but with my Smoker at exactly 20 turns, I kept screwing up the timing.
JP side, I got Heracles'n in Expert difficulty without spending a gem. Sabo/Sabo, Aojiki, Kaku, Relaxation Vivi (freebie turn-delay unit), and GP Usopp. Adapted a Slasher strat to what I had on hand. Also took out Sadi Expert with a high-level Doflamingo friend, after 5 painful failures. Doflamingo's special is so damned good.
Frieza's out... you can't get him as a unit, but the manual drop is pretty crazy: WB, Boa, Ray, Sengoku, all of the talking Straw Hats, GP Usopp, plus Ability manuals to boot. Of course, that's on Master difficulty, where Frieza keeps powering back up every time you take him to 0 HP, DBZ-style.