Need advice

Hello, I am trying to beat a 6-star Tera Raid using my Skeledirge. However my attacks, despite being super effective, hardly to any damage. I tried using stat increases such as HP up, protein, iron, etc, and all do not have an effect on Skeledirge, which makes me assume it's at its max of stats. Anyone have advice? Do I need to change my moveset? Should I have a certain held item? Should I change the Tera type? Any advice will be appreciated! I also run solo raids, hardly ever any online.

For those wondering, here is my Skeledirge's stats:

Level: 100 Tera Type: Fire Held item: Wise Glasses

Hp: 350/350 Attack: 214 Defense (down arrow): 218 Sp Atk (up arrow): 292 Sp Def: 167 Speed: 172

Moveset: Crunch (18 PP) Disarming Voice (15 PP) Thunder Fang (15 PP) Torch Song (12 PP)