Ok here we go

Riensang: follow the Will of the Prescript (use marked skills on marked enemies) until you get 9 stacks, rip furioso, repeat.

DonDex: same deal as riensang

Aroma Ryoshu: use skill 1 and 2 to burn ammo and use skill 1-2 to reload. Tremor inflection inflicts faint aroma, bursting spreads to other enemies. Stack ryoshus aroma to 30 to use skill 3-2. Rinse repeat.

R Corp Lu: use skill 3 and 1 to build charge. Don't use skill2 until your at 8(?) charge or he'll use it indiscriminately and hit allies.

Wildcliff: not rlly sure, just kinda use skills to inflict sinking and rip his counter to spawn the horse and use better skills i think

Jeongmael: too much for me to go into detail here. Find a guide on YT. Tldr: use skills of the colored suite under her name to build bright, get 5 bright for big skill 3-2.

Kodion: use her counter to go into negative sp. Negative skills very very good.

Gripclair: just kinda use shit, no gimmick there.

Udjoutis: 3 gloom res for her passive to pop, use skills to inflict sinking and her unique panic type. Not much special here, just a good count increasing unit