I've always loved the concept of former Imperial Guard soldiers fighting for the T'au and I remember way, way back there were semi-official rules to for them (
http://web.archive.org/web/20080420071331/http://uk.games-workshop.com/tau/tau-auxiliaries/). Here's what I think they would look like in 8th Edition ...
Gue'vesa Team Power Level: 3
Points Cost: 4 points per model
Statline: M---
WS---
BS---S---T---W---A---
LD---
SV+
6"---4+----4+----3---3----1----1----6-----5+
*The Sergeant would have Leadership 7
This unit contains 1 Gue'vesa'ui (Sergeant) and 9 Gue'vesa'la (Guardsmen)
- Each Guardsman is armed with a lasgun and frag grenades
- The Sergeant is armed with a laspistol, chainsword and frag grenades
Wargear Options: - Two Guardsmen may form a Heavy Weapons Team who must take an item from the Astra Militarum Heavy Weapons list
- One other Guardsmen may replace his lasgun with an item from the Astra Militarium Special Weapons list
- The Sergeant may replace their laspistol and/or chainsword with a pulse rifle or a pulse carbine
Abilities:
-
Death to Traitors: Any enemy units with the Imperium Faction keyword that fires at a unit within 6" of a Gue'vesa Team in the shooting phase must roll a
D6. On a 1, they must fire all weapons at the Gue'vesa Team instead during that Shooting Phase.
-
Integration in Process: A Gue'vesa squad may never benefit from any markerlight counters
-
Limited Means of Manufacturing: A Gue'vesa squad may never include a Lascannon, Meltagun, or Plasma gun
-
Tactics Remembered: Any enemy units with the Astra Militarum Faction keyword that fires on a Gue'vesa Team in the shooting phase must subtract 1 from all rolls to hit
-
Untrusted Allies: You may only include 1 Gue'vesa squad for every Firewarrior Strike Team or Firewarrior Breach Team in your detachment. Additionally, a Gue'vesa squad may not benefit from the "Saviour Protocols" ability of Tau Drones
So there you have it, a small, fluffy unit that has virtually no chance to win a game on their own, but can be placed within a T'au gunline and plink away with a heavy weapon ... which is kind of how I see former Imperium soldiers being used in the T'au empire anyway.