In the first and second live-action movies - Teenage Mutant Ninja Turtles Turtles and Teenage Mutant Ninja Turtles II: The Secret of the Ooze - the Foot Clan is a group of ninja thieves and founded by the Shredder in Japan, but later stationed as a street gang in New York City after his arrival in America.  Its members consist primarily of street children and delinquent boys, and they commit more robberies than other, more typical ninja activities such as espionage, sabotage, or assassinations, They made crime sprees in the city, financing their growing crime empire
The Shredder presumably had taken what Foot Soldiers he had from Japan, and began taking kids from the streets upon moving to New York and training them in Ninjutsu himself. His second-in-command is another Ninjutsu master called Tatsu In the films, the Foot use the kanji Oni (鬼?), which translates to "demon" or "ogre", as their symbol, worn in their hachimaki or on their backs. The Foot Ninja were no match for the Turtles individually, however their first major confrontation with the Turtles resulted in Raphael beaten nearly to death and the remaining Turtles forced to retreat; all confrontations after showed the Turtles being able to defeat the Foot easily.
After the Shredder's apparent death and massive arrests by the NYPD, the clan was reduced to a fraction of its former size by the second film. Tatsu tried to take command, but relinquished his claim when the Shredder returned. The clan then kidnapped Professor Jordon Perry and forced him to use a Mutagen so the Foot Clan could create two mutant warriors, Tokka and Rahzar, to fight the Turtles. Although these two mutants were a match for the Turtles in physical strength, the Turtles defeated them by de-mutating them back into harmless animals in an area where Vanilla Ice was performing. The Shredder himself apparently died shortly after while fighting the Turtles as Super-Shredder.
This version of the Foot are dressed in black outfits, have red bandanas on their heads and bug eyes. They usually fight with swords, axes, and other weapons but will fight the Turtles with their bare hands if they have too. They are lead into battle by Tatsu in the first and second movie while Shredder stayed behind. The Foot are were victorious in their first battle with the Turtles but in the second battle they were going down pretty easy. Foot Ninjas are good but most of the time their clumsy and the Turtles appear to be having fun with them in battle. Michaelangelo was taking them down while talking to Donatello and doing his Wheel of Fortune on them at April's shop. When the Turtles first battle the Foot Michaelangelo says "I thought insurance sales men were pushy".
In the fourth film, the Foot is now under leadership of Karai, who has taken control after the Shredder's demise. They have grown in numbers and skill, and offer their services as mercenaries in the film. They are hired by Max Winters to track down and bring in the Thirteen Monsters arriving in New York City. Eventually, they later learn of his intention to send the monsters back to their world with a portal, and that his Stone Generals have betrayed him by substituting Leonardo for the thirteenth monster in order to use the portal to bring in a new army of monsters to take over the Earth. It was then the Stone Generals demand that Karai and the Foot Clan serve them, but they refused, as they want to honor their deal with Winters. Without hesitation, Karai orders the Foot Clan to help April O'Neil and Casey Jones find the last monster and lure it into the portal while the Turtles fights the Generals as well as Winters and Splinter warding off new more coming from the portal. After the final monster is sent in to the portal along with the Stone Generals, Karai and the Foot Clan peacefully part ways with the Turtles, reminding them of the Shredder's possible return.