Update for Season 4 in progress

Tankmo the Invincible! Teemo is the resident rodent of the Toplane, the Bane of every other Champion. Frolic on the Fields of Justice without a single care. Easily kill the Enemy Team whilst being unkillable. Welcome to the World of Tankmo!
-RockJockey

Pros
-Great 1v1
-Anti-ADC = Ashe is useless and in tears
-Good DPS that can Shred Tanks and Squishies alike
-Hidden Power (Blind, Shrooms, Poison)
-Global Taunt (Seriously Overpowered, needs Nerf)
-Nigh Unkillable
-Strong Teamfight Presence
-Very Mobile and hard to catch
-Can Slow and Hurt up to 3 Champions at a time

Cons
-Runs out of Mana
-Mild Loss in Burst and DPS compared with Pure AP Teemo

Teemo is notorious for his Global Taunt, both on the Fields of Justice and in the LoL Forums. Use his Global Taunt to your advantage. Your Enemies will attempt to murderize your cuteness every time you appear on the minimap. Your Enemy Toplaner will continously attempt to exact vengeance on your fluffy tail simply because of your mere existence. This is what you want.

Soon the Enemy Toplaner will find that he cannot defeat you due to your tankiness and obscene damage from on-hit effects. He will call in reinforcements, first the Enemy Jungler and eventually the Enemy Mid. Laugh at them as you press W and hop away to safety while they struggle through minefields of Shrooms. By distracting 3 out the 5 Enemies, you have succeeded, and this will allow your Bot Lane and Jungler to farm freely without interruption.

As the game wears on, you will have pushed down Toplane Towers and will have been able to buy your Core Items. Tankmo's Core Items will allow him to splitpush indefinitely, or if need be, run down for Teamfights and keep your Enemies constantly slowed and unable to runaway. Tankmo on top of all that, can easily shutdown even a fed ADC.

Runes:
greater mark of hybrid penetration Reds: Attack Speed or Magic Pen or Hybrid Pen
Yellows: Flat Armor- to deal with the numerous AD Bruisers.
Blues: Magic Penetration or Scaling MR or CDR
Quints: Movementspeed or Attackspeed or AD or Lifesteal or CDR (Use anything, Tankmo is Very Versatile)


Masteries: Choose the one you like best.

21/9/0 - Full Damage plus minor Health and Resistances

Teemo is a versatile and unique Champion. He can be built several different ways and still be very deadly.

Core:
-Frozen Mallet
-Runaan's Hurricane
-Frozen Heart

Mercury Treads: Can be traded out for any other boot depending on the situation.
-Ninja Tabi is great versus AD AutoAttackers.
-Sorcerer's Shoes for extra MR Pen.
berserker greaves-Berserker Greaves for 20% AS could be bought, but we have enough AS in the build already.

Blade of the Ruined King:
-Current %Health Shred Magic Damage: You can whittle down Tanks and ADCs alike. Combo's with Wit's End MR Shred.
-40% AS allows you to constantly reapply Toxic Shot Stacks
-Targeted Slow: Your Enemies will never be able to run away when you combine this Active with your Frozen Mallet slows and your W Speed Boost.
-Lifesteal allows you to drain-tank your enemies

Frozen Mallet: DA Slows!
-the slow is what makes Tankmo so endearing, your enemies cannot catch you and they cannot run away. Multiply that by 3 when you buy Runaan's Hurricane
-700 Health gives Teemo the necessary buffer to not be burst down.

Frozen Heart: Multiplies Teemo's Invincibility.
-95 Armor: Prevents you from be eviscerated and burst down by enemy ADCs or Bruisers
-20% CDR: Helps keep the enemy Permanently Blind so that you never take damage
-Aura: 20% AS Reduction to Enemies: this along with the rest of the stats multiply Teemo's invincibility.
-400 Mana: More Mana, more Blinding Darts and Mushrooms.

Runaan's Hurricane: 3 Targets instead of 1
-70% AS bonus is huge
-Can apply on-hit effects to 3 champions at a time (i.e. Toxic Shot, Frozen Mallet, BotRK, Wit's End, etc...)
-(Runaan's Hurricane should be the third Major item purchased, BotRK can be purchased earlier instead)

Wit's End: MR Shred
-MR Shred increases the amount of Magic Damage enemy champions take from your Toxic Shot, Wit's End, BotRK, etc...
-MR to survive burst from Mages
-42% Attack Speed = More Toxic Shot Stacks

Other good items for Tankmo include:
Randuin's Omen: More Health and More AS Slows, good combo with Frozen Heart
Nashor's Tooth: AS, AP, 20% CDR, on-hit effect
zeke's heraldZeke's Herald: 20% CDR, Health, Aura LS to boost your team's ADC
Liandry's Torment: Health, AP, %Current Health Shred
Muramana: Lots of Damage, Lots of Mana, really cheap
Zephyr: Last item to build, replaces boots

Tankmo can duel nearly anyone, draining their Health away. It doesn't matter if it is a Tank, OffTank, AP Mage, or ADC. Tankmo is equipped to prevent the enemy ADC from doing a single point of Damage.

Blinding Dart: Blinds 1 target for 2.5 seconds
Frozen Heart: 20% AS Reduction
(Randuin's Omen for even more AS Reduction if you buy it)

Just those two effects will reduce their DPS to ZERO. And all the while you can keep pricking them with Darts that eat away their Health. The Enemy ADC will live in fear of you because they cannot out-duel you.

Frozen Mallet + BotRK + Runaan's Hurricane = No One Escapes
-Enemies can never catch you.
-Enemies can never run away, slows forever.
-You can always outrun them.
-Multiple Enemies' Health drains quickly

Tankmo the Invincible is fun for you as you watch your Enemies uselessly try to kill you.
Tankmo the Invincible is infuriating to your Enemies as they are powerless against your Global Taunt.

Have Fun Summoner!

Soviet Swain Approves Tankmo!
-RockJockey