The similiarities between TMNT and Violent Storm.
Both are arcade games made by konnami. both are beat em' ups and share
common development team.
I have noticed some intentional similarities,

* In violent storm the 4th stage boss flies in a similiar way
 to Super Krang like in TMNT .
* If you break the fire polls in violent storm's 4th stage, you'll notice 
 they are similar to the laser turrets from TMNT's technodrome level.
* the boss music in VS's boss 3 and 5 sounds very similiar to the
theme of super shredder at the last level.
* VS's boss Sledege obiously looks like a ninja turlte.