M.E.C.H (Mercs of Eternal Coreship Hordes) is the REAL final boss of Gradius 93, According to the data. this was a huge Core of one mothership filled with hologram ships from the past.
At first, M.E.C.H just appears to be a giant core. After that, the screen flashes white, and the background turns into a white vortex. Then, M.E.C.H takes on the form of Big Core, which eventually, if the core is destroyed or if the player takes too long to defeat it, disintegrates. Then, M.E.C.H will take on the form of Tetran, and will also disintegrate with the same conditions. Finally, Covered Core appears, creating a shield of missles, after this, Covered Core explodes. M.E.C.H will return to normal, and will also begin to dim. When it's color turns grey, it creates a gigantic explosion, even turning the screen white. After this, the game is finished.
M.E.C.H's attack pattern is very similar to O.V.U.M, it's name is also very related.