It all started back in August 2011 on the HTC Evo 3D running Gingerbread, where j4n87 (now j to the 4n) started getting into reverse engineering the Sense framework.
His first smali hack was a simple one, to remove the horizontal recent apps bar in the notification pulldown in Sense 3.0.
The thread is located here. Basically it was pretty much copy and paste from an original mod from romanbb.
But it was j4n87’s introduction into the world of apktool, reverse engineering, strong coffee and sleepless nights and it gave him a taste for more ambitious projects.

He liked to play with his Evo 3D, but soon got bored and began looking around to see what other mods there were out there. His second project was the port of the famous “Zeus Mod” to the HTC Evo 3D GSM, you can find that thread here.
A bit later then he found myn’s WarmThreePointThree ROM, which was only available for the CDMA version of the Evo 3D.
The ROM however did incorporate “Warm Tweaks”, originally created by romanbb for his Bulletproof ROM on the Sensation.
Impressed by the features “Warm Tweaks” offered he set about trying to port it to the Evo 3D GSM as standalone version, and in November 2011 Leedroid Tweaks  was born.
Although titled “Leedroid Tweaks” it wasn’t actually anything to do with the Leedroid ROM series, and was only so named because Leedroid was the ROM he ran at that time and used as the base for his Tweaks.

During the development of Leedroid Tweaks j4n87 got in touch with several XDA developers. One of them was Joelz (now renzo.olivares),
who helped out in the early days with porting some tweaks from Warm Tweaks to Leedroid Tweaks.
Initially Leedroid Tweaks was really just a port, without any unique new features as j4n87 didn’t yet have the experience in smali to implement new features of his own.
That changed pretty quickly though, and just a month after the initial release of Leedroid Tweaks j4n87 released version 3.0.0 which contained new and unique tweaks, not previously available anywhere on XDA. Two of them were a Screen On quick setting, which let you turn off the Auto Screen Off timeout, and custom overscroll colors.

In early 2012 ICS was released for the Sensation and Evo 3D. Since the frameworks of both were pretty similar, j4n87 began to port it to the HTC Sensation and later on also to the HTC Flyer
Leedroid Tweaks rapidly gained popularity and was incorporated into many ROMs across a number of different devices. Even redmondpie posted a news about it: “LeeDroid Tweaks” Brings A Wide Variety Of Extra Features And Functionality To HTC EVO 3D, Sensation & Rezound 

When the One X was released j4n87 began working his smali foo there too (One X Leedroid Tweaks).
As he now found himself supporting several devices on his own, j4n87 was very happy when out of the blue a previously unknown guy by the name of m0narx  offered to help out.
From then on m0narx supported Leedroid Tweaks on the Sensation and j4n87 took care of things on the One X. m0narx was a tremendous help, adding scores of new features. He was and still is one hell of a dev!

Altough Leedroid Tweaks was a huge success j4n87 had bigger plans. He wanted to have his own ROM and team, and so was born Team Pkmn.

Here is an extract from the original chat log in which j4n87 and Joelz came up with the name:

j4n87: Team ANAL (AmazingNotAsLoosers)

Joel: lmfao

….

Joel: TEAM FAIL lol
Team OWN

j4n87: Team PWN

Joel: there we go…we have a winner

Ich: serious?

Joel: yes

….

Joel: Hero ROM
mm TEAM Hero
sounds cooler

j4n87: Team Pokemon

Joel: yes
TEAM Pokemon

j4n87: yeah

Joel: and yes im serious..

….

Joel: …or we can just be Team PKMN

j4n87: yeah, sounds actually better =D

Initially the team line up was m0narx, Joelz and me. For whatever reason the ROM didn’t take off as we had expected, although at the time it was second to none. People assumed the ROM would be completely Pokemon themed, which wasn’t the case. It was actually just the wallpaper and a really funny bootanimation and sound.
So we decided to relaunch. Before that however, we needed to get more devs on board. Given the popularity of Leedroid Tweaks lots of devs saw the potential.
So Turge, viperboy, Virus and vinchenzhop, who are all still part of the team joined the party. Viperboy and vinchenzhop had their own pretty popular ROM series already and didn’t want to drop it completely, so we needed a fresh name for the Team and the ROM, a name which would link to the viperboy viperom series. It was a pretty easy decision, and we settled on naming the ROMs with a “Viper” prefix and chose “Team Venom” as the team name.

And the rest, as they say, is history!