The robotic Foot Soldiers Mark I were the main soldier's for the 1987 Shredder in the 1987 TMNT series.
When Oroku Saki took command of the Japanese Foot clan after getting rid of his rivil Hamoto Yoshi, he used the clan's human ninja's to do his dirty work. However after meeting an alien criminal called Krang from Dimension X, a robotic army of Foot Soldier's were made, replacing the human ninja's.
The Foot Soldier's were not very smart or formiddible in combat. The Mutant Turtles could defeat and destroy them without any difficulty.
Shredder and Krang tried to make them more intelligent and stronger in battle, with Krang's new equipment they tried to make a Foot soldier called Alpha 1 smarter, it worked but worked too well and Alpha 1 led a revolt against Shredder and Krang who had to call for help from the Turtles. When Alpha 1 was defeated the remaining Foot Soldier's were under Shredder's control once again.
In Turtles Forever, the Foot Soldier's along with the 1988 Shredder and his alien sidekick Krang enter the world of the 2003 Teenage Mutant Ninja Turtles by accident along with the 1988 Turtles.
Like in the 1988 series, the robotic Foot soldier's prove to be very weak and clumsy in battle. When the 2003 Shredder Ch'rell and his daughter Karai took over the 1988 Shredder's technodrome they upgraded the soldiers into the Foot Soldier Mark II which were much stronger, robust and faster when compared to the older version.