BS13 is a solid platform for most offensive weapon options. HMG and MULTI sniper rifle are the most popular offensive options. X visor on the multi sniper makes it a viable option in close range too.
The MULTI sniper rifle, if correctly positioned, can take out total reaction HMG bots without smoke (-12 due to cover, camo, surprise shot and -3 for the HMG range outside of 32").
Combi rifle + light flamethrower: The combination of a burst weapon with a template weapon can force your opponent into making some poor decisions, if they dodge, fire the combi, if they shoot, lay down the template. Given that they can show up in unexpected places, you might even get to catch a trooper in a marker state under the template while targeting someone else. Given the high point value of the intruder itself, one has to be careful when declaring the template attack when taking return fire.
Grenades: are typically available on profiles that don't like close quarter engagement (lieutenant, HMG). A potential strategy is to deploy these prone on a building. If an enemy gets close, speculative fire a grenade. If the target is within 8", the target number is reasonable (9)
Adhesive launcher: this is a great platform for an adhesive launcher when shooting at tags through smoke. When done right, they're shooting back at -12 (camo, cover, surprise shot, shooting through smoke), your target number should be 13 or higher and they dodge at -9 (-6 for being a tag, -3 for surprise shot). However, the high SWC cost of this loadout (1 SWC) makes this a rarely seen profile. It is worth considering in a mission like hunting party where due to the elite troop type all intruders get access to another adhesive launcher.
ARM3 is decent medium infantry armor, in cover there is a decent chance he ignores hits. However it is advised to not run the risk and stack as many modifiers in your favor as he only has 1 wound.
BTS 0. Unfortunately this makes him an easy target for anything that goes against BTS.
Hacking device: The hacker allows you to slow down the approach of enemy HI, REMs, TAGs and hackers. The marker state protects the hacker from being singled out by killer hackers.
PH12 is reasonable, however, if you're dodging you're probably doing it wrong.
Camouflage: To keep your valuable offensive piece safe during the reactive turn, spend an order to re-camo him.
The Intruder Lt in missions like firefight, decapitation or hunting party is an excellent choice. It gives you access to an Lt in a marker state that cannot be easily targeted by enemy troops like impersonators or superior infiltrators. He still needs additional protection from these troops by putting a buddy with a template weapon nearby.
When deploying the marker make sure he is positioned in such a way that he cannot be caught in blast (circular or teardrop) range of one of your other troops. Token state even protects him from speculative fire.
MSV 2 + smoke: Throw regular smoke, move the intruder into the firelane, open up. Repeat. This can also be used to target camo markers with discover+BS attack. His MSV makes him especially good at discovering.
Multiterrain allows them to move unimpeded through difficult terrain in missions like rescue.
Hacking device, stealth: The stealth granted by camouflage allows your hacker to walk into repeater range without taking ARO's (outside of line of fire). This is important if you want to capture an objective (be careful because capturing an objective is usually considered an attack, which will expose him to hacking AROs).
Camouflage -> surprise shot: Use surprise shot to stack modifiers in your favour.
Camouflage mind games. The Intruder is a well known offensive piece in the game. Most players facing a nomad army expect to face them. The Intruder is the only non-infiltrating regular camo profile in the nomad army. Hence, most people will assume that a camo marker in your deployment zone is an Intruder. If the marker is on a building, most players will expect the HMG or MULTI sniper profile. Especially if a unit with smoke grenades is deployed nearby (Lupe Balboa, Jaguar, Morlock, McMurrough). Most skilled players will tend to avoid leaving pieces exposed in the firelanes overlooked by this camo marker. This mindset can be exploited by faking the presence of the Intruder by using a minelayer profile or by deploying another trooper with camo in this position. You can then project threat without actually having the piece present. The Zero minelayer profile works best for this trick (only in vanilla Nomads).
MSV 1-2 and high burst weapons. The Intruders are not great reactive pieces unless they're in the midfield in suppressive fire. They are also vulnerable to white noise.
Sixth sense Lvl 2 negates most of the penalties imposed by the smoke combo. When facing a link team, an Intruder can still target individual pieces one at a time, without having to worry about "slicing the pie", as only the piece that is being targeted will get to to ARO. The modifiers won't favor you as much as otherwise especially when dealing with other long range weaponry. If possible the Intruder should target other profiles first, removing some of the link team bonuses before taking on the more risky encounter. To counter this, effective positioning of the link team members should avoid this.
Due to his low BTS, ammunition that targets this going to be more effective, even a lowly flash pulse.
Shock prevents Intruders from being recovered. It is especially useful if they are being used with low cover so their unconscious bodies can't be targeted.
Bring smoke grenades. In Corregidor Jaguars are the most common source, but Lupe Balboa and McMurrough are other options. In vanilla Morlocks are another good cheap option.
Intruders are ideal doctor targets. They usually go down near the safety of your deployment zone. Bringing a normally deployed doctor can heavily reduce how often you lose an Intruder to bad luck, or add the ability to recover after using them in ARO. 3 ARM isn't that tough but it's enough to leave them unconcious decently often.
HMG and MSR Intruders can be used in a small secondary combat group to open up the board for the main group. This is a good tactic for enabling an alpha strike without draining orders. However combat group 1 allows the Intruder to reposition and be used much more, something especially useful for the HMG.
The MULTI sniper is best deployed in the back of the field, if possible prone on a building with a source of smoke nearby. Giving him a view of most of the table is a generally accepted tactic.
The HMG is best deployed as close as possible to the edge of your DZ. He can be on a building, but generally he needs to move around a little bit. Buildings with catwalks between them are a good option so he can move from one firelane to the next.
If you go second your Intruder should be in total cover. He is too vulnerable (see counterplay) to leave out. Prone on a building is a good option.
Active Turn Role
The HMG and MULTI sniper are equipped to take out almost any ARO piece. Use them to mop up the reactive pieces your opponent has left out to clear the advance for your units that like to move up the table.
The hacker and combi rifle profiles need to move up the table to be effective. Use coordinated orders for efficiency. Bring smoke throwers along. The hacker is excellent at capturing objectives. The combi likes to be left in suppressive fire in the middle of the board. Consider re-camoing the hacker for protection until your next turn.
Intruders are a high point investment and since they only have 1 wound are best hidden in the reactive turn.
If you're moving up the field with a combi or HMG profile, put him in suppressive fire. If the MULTI sniper is in a position where he can outrange anything that can potentially target him it might be worth considering leaving it peaking out.
Leaving an Intruder in ARO is usually an acceptance of losing it. Make sure the enemy can't pin you down after you lose the Intruder.