Well maotd already said a lot you need to know about Vanilla Cattleya.
Maybe you will find some additional info in my vote.
Stats: High Attack, n1 defence, low HP. She needs Attack for her Skill set. The other two stats are not that important for her.
Skill: Like maotd said x2,4 damage to all enemies is probably the best part about Cattleya. Thumbs Up
Abilities:...and here we are. 50% Light Gauge...Hmmm since she is no Solarblast Girl the only incident where this would come in handy is Whale Ship Battles. Not a fan.
Increases Attack for 3 Party members by 40%. That's an overall group atk increase of 120%. I am not a fan of random buffs since you want to buff your hardest hitting girl in the group and RNG buffs do not always provide that.
X1,2 Skill Activation is definetely good but it's also rather standard for a lot of 6*. The rare superior Skill Activation Ability (1,36 multiplier based on Skill Level) would do good for her overall usability.
18% Skill Damage for the whole group is the highest grp Skill Damage buff in the whole game atm. So Cattleya fits in a Skill Damage Team build around Maple or/and promoted Anemone (Radiant Princess). Sadly her other buffs (atk buff and filled Light Gauge) are really lackluster compared to other Skill Damage Girls and that's the reason she is outclassed in this specific archetype and other archetypes as well.
Conclusion: Cattleya suffers from being an old Rainbow. Due to the Powercreep she is outclassed in "Good Stuff" teams and also specific archetypes she tends to fit in (Skill Damage). Her Radiant Princess Form is definetely the much better version of her. Lets hope she gets a n1 buff in the near future. She would definetely benefit from a fifth Ability.
My Vote: Sry Cattleya it's only C-Tier for me.