Tinnin Path::
By far the easiest group of NMs. None are too much of a journey to get to, and most are easily low-manned.
Tier 1:
Chamrosh: Easily low-manned, only thing to be concerned of is post charm. After charm will spam AoE's. Spamming low dmg spells on him to keep him spell-locked very beneficial.
Cheese Hoarder: Actually easier with a small group. Avoid mines, some can do up to 500 dmg. Behavior similar to Qiqirn NM's in Salvage.
Vulpangue: High dmg wind sheer attack, can be lowmanned with melee / tanks having Shadows.
Tier 2:
Iriri Samariri: Not recommended low-manning. Challenging path to get to a safe place to kite. Multiple Porogo Repops in spawn area make this a challenging fight that needs to be done quickly:
Iriz Ima: Easily low-manned, an elephant without fleas that's susceptible to grav.
Lividroot: Haven't fought personally, so can't say either way.
Tier 3:
Armed Gears: Low-man group preferred, tp attacks are bad as with all gears, so avoid giving tp, easily kiteable. BLM's will cast opposite nukes to the en-spell he uses.
Dea: Kiteable, recommend pulling to a safer area. Stick Grav on it, sneak/invis away to one of the towers. First time we did this we pulled all the way across the zone without problems to the Whitegate entrance tower.
Gotoh Zha: Low-man group feasible, but won't be a walk in the park. Starts BLM and manafonts, switches to WHM and will Bene. Firespit has an incredibly long range, recommend fire resist for PLD/NIN tank, and using BLMs / RNGs to dmg. Can be kited around the tower. Do NOT break his weapon, seems to have H2H skill so you'll lose 2 shadows with each attack round if staff is broken, making kiting and/or straight tanking much more difficult.
Sarameya Path::
Much more difficult NM's and NM locations in the upper tiers. Some can be low-manned, but sometimes getting to the spawns is more difficult than the NM's themself.
Tier 1:
Brass Borer: Spams cannonball, an aoe Burn + dmg spell, and links with other wamoura princes in area. Can be low-manned with moderate difficulty, straight tanking is a must due to lack of kiting in near vicinity to NM.
Claret: Can be manaburned
Ob: Pup should be included, makes the Nm a piece of cake.
Tier 2:
Dextrose: Extremely long path to get to this NM, including running by a bunch of True Sight mobs. Highly recommend a sac-puller to clear the way. Because the NM needs to add links, I wouldn't recommend low manning this, but I'd be pretty impressed if someone could. Basically have around 12 minutes to finish the fight before scorps will repop.
Reacton: Another long long hike to get there. If you're only doing one, possible to kite by passing through a drop off close to the area, but that means you have to do the hike again for multiple pops. If you're not, you have a limited amount of time to do it because of Friar Lantern repops.
Anantaboga: Not confirmed, but in about 6 fights I've resisted 80% of Virelai's using 3x's Koenig Armor, whereas others are getting charmed almost every time. As long as you can avoid other Dahak's and undead that spawn at night, can be low-manned. Do NOT silence, do NOT buff yourself with anything other than shadows, and you'll be fine.
Tier 3:
Achamoth: Due to high dmg and auto-regen, as well as self-curing for all debuffs put on it, I don't think this is feasibly low-manned, but I could be wrong!
Nosferatu: Did last night with 11, I think we could have done with a couple less. Challenging fight none-the-less, taking to zone is a must. If solo-tanking, be sure to DoT as soon as charm goes off, then have everyone zone to clear hate. This helps the tank regain hate after charm, as well as ensuring party survival. If you do low-man this, DoT's + Nukes then zoning would be the strat.
Khromasoul. Could be low-manned with zoning method mentioned above. Vital that if adds are popped, they are immediately zoned by the entire party/ally.
Tyger Path::
Probably middle-ground between Tinnin (Easy) and Sarameya (Difficult) paths. Some NM's are a trek to get there as with the Sara path.
Tier 1:
Chigre: Easily low-manned
Lil Apkallu: Traditional party will have no problems, won't link with any mobs in existing area.
Velionis: Haven't done personally, but I'd assume since it's a skeleton it'd be much easier with MNKs.
Tier 2:
Verdelet: Straight tank and just take it out, extremely weak NM.
Wulgaru: Kite around poles as mentioned by others, another easier NM.
Zareehkl: 75k HP, if you're going to do it, probably want to try to pop Lamia 19 first to give you time. There's a small cave near the spawnpoint that can be used to avoid other aggro.
Tier III:
Experimental Lamia: Because of Adds that must be killed, low-man group not recommended. I suppose 3 extremely skilled RDM/NIN could each solo an add (Do not be in party while doing so), but would need good communication if assistance is needed.
Mahhlaef the Paintorn. Fast cast on everything, but by pulling to Khim area should be kiteable and thus low-manned. Issues will come when shields are up, but probably will just lengthen the fight.
Nuhn: Wiki says kiting extremely recommended, I say just melee burn it. No real advice for low-manning from my perspective.
Tier IV's: An EXTREMELY skilled group could theoretically 6-man Tinnin, but even so, it's a week's worth of work to get the pop-items, don't think you wanna take the risk of losing all that for epeen.
Sara: GL, lol
Tyger: I'd assume no chance.