Holy Flan Raid Boss Event

She has the elemental and attack type advantage made to be able to solo Holy Flan without even needing to be at level 120. Tetra Sylphid esper can also provide some good boosts since she has Wind ATK+, Aquatic Killer, and Missile ATK+ if you want to use someone like Corwell or Lu・cia.

Pretty easy for Oberon to hit the max damage cap since he has good ATK and buffs, but he can also lower Pierce resist from the main job ability. His LB being able to reduce all elemental resists is a great way to boost teammate's damage as well.

Glaciela has a 3 hit pierce ability to help with chaining. Together with other Pierce attackers, she will be able to hit max damage cap per hit.

Viktora can reduce DEF from main job and AP increasing counter ability for some self sustain. There's also Aranea and Lasswell to make a team of Ice Pierce units to have an easy time with the raid.

Lucio's still useful to bring for the raid since he's part of the raid bonus and has a 3 hit ability that can be changed to Pierce-type to help with chains. But he can end up breaking pierce chains since he only has 3 uses of the 3 hit ability, and lack of AP will make him use normal attack, which is Slash-type.

Noctis is just useful for PvE in general since he has many attack types, including Pierce, and can reduce enemy's DEF and resistances. However, he only has 3 uses of the Pierce attack before going back to slash, and he will need Illusory Bell to help with AP.

Ramada is a pretty decent filler since she has decent ATK, cheap AP moves, and a small benefit if she uses Clairvoyant Astrologer. This lets you use Illusory Bell on another unit and have a DEF down ability from the VC.

You won't really need to use different units against Gold Cactuar since it's also weak to Pierce. But with no hate increase on Gold Cactuar itself, it can make the raid run faster if you have a unit with an area attack.

Other than that, you can pretty much stick with Lucio and bring any unit any raid bonus unit that you might have.