I almost forgot Cherry. So, let's go for her on paper.

Stats:
HP: She is on the good side. She don't actually needs them that much but it's good to have a good HP stat for a Debuff girl.
ATK: She is really close to the botom and that's a shame. With better ATK she could be slightly better but... nah. She is very weak on that side.
DEF: Good defense. Not the best but still above the 3k threshold and that's good for me. But like HP, it's not supposed to be her best stat.
She has really nice defensive stats but... she is not a Counter girl. A bit too meh for me.

Skill
x3.8 damages on 2 enemies, 34% skillact.
She is one of the few natural 6* with that kind of ability... and you already know, I don't like it. It can be useful for some Aquashadows bosses but it seems last ones are really toughs. And I'm not sure Cherry was strong enough to fight them.

Abilities
+20% ATk for all
Classic good ATK buff. Always welcome to raise a bit her bad ATK and support friends.

-20% Attack for all enemies
That's her best ability. -20% for all is (if I'm not wrong) the best ability of that kind. Most of them are +15% for all or +20% for two. This made her one of the best debuff girl.

+40% ATK and +18% damages on boss fight for herself and 2 allies
I put the last two abilities toghter because they're very similar. First, why? Why a such good buff for only herself and 2 random girls? With her bad ATK stat and her meh skill, she is not the best to receive theses buffs. Remains 2 allies. 2 RANDOM allies. It's not bad but you can't rely on it to give an amazing buff to your main girl (someone said Kerria?).
She would be far better and reliable with a weaker buff on the whole team. But she only has this. Not bad but it's more a bonus than an ability you will choose for itself.

Team Build
Cherry is not bad but due to her strange stat+skill+ability combo she don't have many team options. Like almost every rainbows you can use her in most teams as placeholder but unless some other 6*, she will not brings something awesome. Even -20% enemy ATKis not that good alone.
Her only true place is in a debuff team where she can have a solid place with her -20% ATK for every pests. And... that's all. And even with that really good debuff, she is outclassed by a lot of other debuff girls.
If you want to use her in single or two boss battles, a girl with -20% on two enemies and better stats/abilities will be better.
If you want to use her in a 3 pests fight, her skill can be a problem if she don't hit the rights targets.

Conclusion
Cherry is a strange girl with almost nothing coherent. She has good Counter stats but she is not counter, she has semi self ATK/damages buff but she is weak and don't have a strong single target skill and she has a really cool -20% debuff for all the a skill not for all.
She could be good if she was more focused on one job instead of trying to be everything but nothing good.

Final verdict:
I'm a bit rude with her. Despite all her flaws she is still a nice debuff girl (and her Bride version is really cute). I will give her a C Tier for her utility in debuff teams. Sorry Cherry.
Note that even her Birde ver. after 6* promotion have the same kind of uncoherent flaws with ATK based on remaning pests and a single target skill. And, just to say, if regular Cherry and 6* Bride Cherry swapped their abilities, they would be both better.