LOL is it just me or did they revert the ingame notice from "non-revoked item conditions" back to "conditions" again? Maybe because they updated it yet again with a crew log section now and the rest was an old copy/paste. Or they freaked out about people reading that as "just abuse the glitch to your heart's content".
So I made a list of potential rainbow targets for people who would find themselves with a few thousands tablets lying around. Obviously high priority for your most used/powerful legends and RRs. I'd say any dual legend is worth rainbowing and also any RR with either special CD reduction or double special( mostly V1 Big mom batch). Then you can focus on pinch healing on your favourite units since it can be a lifesaver and also RCV bind on your Enel/zombie team. Also for your shooter team, try get as much barrier pierce as possible of course.
- Luffy/Law : pinch healing + critical
- Koala/Sabo : pinch healing
- Barto/Cav : slot bind (full removal)
- Warco : slot bind (full removal)
- Inu/Neko : critical
- V1 Big Mom : critical (helps a lot on her auto nuke)
- V1 Katakuri : because his 6+ is incredibly strong and will carry you through 2 months worth of content if you don't pull
- Lucy : similar to V1 Katakuri, though not a very strong 6+, still a decent ATK booster option for O-tama ranking
- Corazon : RCV bind + special CD reduction (<--- key for a lot of challenges/tougher content)
- Magellan : pinch healing (so good in Kizuna)
- Enel : RCV bind
- V1 G4 PSY Luffy : special CD reduction, starts the quest at max special, massive nuke, he's a decent option for fast farming teams
- Shirahoshi : RCV bind
- V2 Katakuri : RCV bind
- V1 STR Elizabello : special CD reduction (by 15 turns!!! his special will be available straight away) niche but incredibly useful unit with his AoE nuke special, helps so many challenge/farming teams
- STR Zeff : special CD reduction, makes his special available straight away too
- STR Smoothie : double special, so good since it means 4 turns of paralysis/burn/bind/despair removal and 10k heal
- DEX Perospero : double special, actually a very useful unit that is kinda underrated, CA booster for 3 colours + reduces crew special charge, he's still relevant nowadays on JP, people used him to run O-Tama ranking recently.
- QCK Inazuma : special CD reduction, incredibly niche but yet irreplaceable for some zombie Kizuna farming
- PSY Kuma : double special, invaluable unit when you're not a whale since he allows you to cheese some very tough content. His LB doubles your chance at insta kill! Plus he packs great utility, could be MVP for you in the future Halloween Luffy raid
- PSY Camie : double special, allows her to delay AND provide a conditionnal ATK boost + 4 turns of special bind removal
- INT Chobro : special CD reduction
- INT Ain : double special, 4 turns of enemy buffs and crew debuffs removal and potentially healing too, pretty great
- INT Valentine Koala : special CD reduction
- INT Galette : special CD reduction, helps so much in Kizuna when you know you can't stall long enough for that one unit, she'll start with her special ready and will help reduce special charge time for another unit
- QCK Bobbin, PSY Hina, INT TS Nami : because you use them all the time
That's all I can think of right now. I'm sure I missed plenty of other units so feel free to add your own picks :)