Tank-melee style: stand under Graardor to avoid his ranged. Use Protect from Melee. Kill Graardor, then minions quickly.
Use Bandos/Torva gear with Abyssal whip or Scythe. Stand south of Graardor to avoid ranged attacks.
Saradomin/Armadyl gear. Dodge ranged attack by staying at melee distance. Switch prayers as needed.
Not recommended due to Graardor's magic weakness being minor; melee is preferred.