This build works by using the Mecha set buff with a high status weapon (such as the [Daikyu], [Nagantaka], etc) and giving the Kubrow as much ability to do damage as possible, therefore giving it more survivability and usefulness without losing too much utility.

Why you would use a Sahasa

The sahasa is quite popular, arguably the most popular Kubrow. It is starting to become a frontrunner companion for Eidolons for its extra energy provided. And all round it is a useful companion due to its damage ([Ferocity]) and utility ([Dig]).

Damage

[Maul] gives the kubrow extra damage.
[Ferocity] gives the dog a finisher. Ferocity Gif.

Status

The dps mods; [Frost Jaw], [Shock Collar], [Flame Gland] and [Venom Teeth], in whatever combination of elemental damage you want.

[Mecha Overdrive] and [Mecha Recharge] work in conjunction with your warframe's [Mecha Empowered] and [Mecha Pulse]. Using all four will grant you many more times that the Kubrow proc's the ability, but the full set is not required. What the set does is make it so randomly sometimes when you are killing targets, killing one will cause a spread affect to nuke the enemies around it (as can be seen in the video and link).

To quote the wiki, when pairing a weapon with the set

The bonus is calculated from a weapon's total modded status chance before multishot. This makes high-status shotguns a particularly good choice, as they should be built to [Reach] 100% status chance before multishot, conferring the full 60% bonus.

Alongside this, when your kubrow gets a higher status chance, the dps mods ([Frost Jaw], [Shock Collar], [Flame Gland] and [Venom Teeth]) can give the kubrow a strong amount of elemental damage.

Survivability

Link Health gives the kubrow extra Health. Remember if you are on something like [Hildryn] then Link Shields may possibly work more to your favour. This mod works with "base" warframe modded health, not how much health you have each moment in combat.

Utility

[Fetch] lets the kavat loot for you.
[Dig] allows the dog to give you energy, health, ammo or mods. Dig Gif.
[Primed Animal Instinct] allows the kavat to show you enemies and loot on the map.

Other mods

If you are looking to change up the build, Primed Animal Instinct is the default which can be exchanged out (as they only affect you rather than the kubrow).
[Medi-Pet Kit] can be useful if your kubrow is dying often in the content you are doing.
Link Armor is also useful if you are bringing a frame with a high modded armor.
[Hunter Recovery] allows the kubrow to heal your warframe.
[Primed Pack Leader] (or [Pack Leader]) allows your melee hits to heal the Kubrow.

Make sure you set up the proc' abilities such as [Dig] and [Ferocity] in the first slots on the left, because it will then proc' them most often.