The Sergeant's Lanka is capable of dealing extremely high damage, but it bears low fire rate with projectile travel time in return, keep moving from cover to cover to avoid being shot.
Just like all Corpus, the Sergeant's shield is weak to Magnetic, Cold and increased Impact. Alternatively, you can use Toxin damage to bypass his shield completely. For example, a fully modded Acrid based on Toxin damage can take Anyo down in as little as one shot or a Maxed Strength On Mesa's Ballistic Battery can take him in one shot.
You can reveal his weak point by shooting off his helmet. Shooting his head will deal increased damage.
You can track his location while he's cloaked with his blue objective marker, the aura Enemy Radar or the mod Enemy Sense. Electrifying and flaming him will also leave the elemental after effects without actually seeing him. Bleeding caused by Slash Damage can also serve the same purpose though the effect is harder to spot.
Shooting him with a weapon with travel time like Boltor and Kunai can damage and show him his location, as the projectiles stick on the invisible Anyo (In the case of throwing knives, the light trails from the weapon will follow the boss).
Resorting to melee attacks is a good strategy as it will still hurt the cloaked Anyo, while preventing his shields from recharging. (Bug) This can also be used to easily solo his boss fight, as melee blows will prevent the Sergeant from firing his Lanka or counter-meleeing and the weapon is harder to use in close quarters.
Key to avoiding damage when getting up close is taking advantage of the boss room terrain or using your Warframe abilities. Ambushing or closing distance quickly will prevent him from getting off many shots at you.
Utilizing Warframe AbilitiesEdit
As mentioned above, abilities that can quickly cover ground such as Excalibur's Slash Dash or Zephyr's Tail Wind are useful for quickly closing distance with him for melee attacks in addition to doing direct damage.