Thanks to Zell for giving me some great suggestions. Updated the guide a little bit.

+rep to zell for his detailed review. I really feel the same way he does and will vote when it's more complete.

You're missing something but for now i would like to give you + 1 for some awesome builds and love that you actually get wards :)

Even know this guide has many useful hints and apprehends the basis structure of Trundle builds while touching on his mechanics via Skill Sequence it unfortunately becomes bland due to a severe lack of illustrations thus resulting into a lack of visual interpretation & analogies for clarification towards the reader. While you've demonstrated understanding of his skill mechanics in some manner (via Skill Sequence) you ought to go in more depth (aka give a "Skills" chapter) as he does have quite a unique kit: Pillar of Filth one of the two only "walls" in the game (the other being Crystallize) & Agony being the only (as far as I know) skill to apply % reduction before taking into account any flat or % penetration. I'd be happy to vote once some modifications and improvements were made and adding some bbcoding.

Pros / Cons

"Can 1v1 any jungler" is basically repeating the same previous point of "Can demolish the enemy jungler" but with less emotive vocab, so it serves no purpose. I strongly disagree with "Predictable jungle path" as said hes a versatile jungler who can start where ever he likes while it is preferred to start at Wolf/Blue there's nothing stopping him from going Golems > Wraiths > Wolves > Blue if the occasions arises due to enemy invasion or lack of team support making it dangerous (the horrors of solo queue!) like other junglers such as Lee Sin, Nocturne, Shyvana etc. As such its appropriate to add it to his Pros in having a - "Adaptable jungle path".

Should expand on points like "No AoE jungle skills" in giving an example of who may so, "No AoE skills meaning slower clearing time then other top junglers like: Shyvana, Udyr, Lee Sin etc. Great territory control through Pillar of Filth and Contaminate is surely enough Pro. As well as being one of the few champions to have a wall effect with Pillar of Filth being able to block off enemies escape or engage path.

Jungle Route

Should include alternative jungle paths in case of an enemy jungle invasion or other emergencies forcing you to adapt.

Runes

I too prefer Greater Mark of Attack Speed since it provides faster jungle clear time and with Greater Quintessence of Desolation & 2-3 Greater Mark of Desolation suffices to penetrate the armor of the majority of camps. Otherwise all the other runes seem fine.

Masteries

May as well include a defensive masteries build to add to the choices that being 9/21/0 which does seem a lot more appropriate for the support builds.

Items

Since you've added Sight Ward to the item build I guess you should give it is own paragraph to describe how to ward key objectives in instance: Dragon, Baron, Blue etc.
In the second DPS Trundle build you may as well get Warmog's Armor first before Frozen Mallet if your going to get it right after as it provides you time to farm its passive. Same goes for the support builds. To be honest it would be more beneficial to get Atma's Impaler right after buying either Warmog's Armor or Frozen Mallet to grant you both some offensive power and defense as you don't just want to be a big blob of health doing hardly any damage.

Also, getting Randuin's Omen instead of a second chunk of health item either being Warmog's Armor or Frozen Mallet would give more effective mitigation since it gives health, armor & a great passive which reduces attack speed. To have both Warmog's Armor and Frozen Mallet is just redundant.