Plate

Plates (プレート) are items found in four games from the original Mega Man series.

Mega Man 5
There are eight plates: M, E, G, A, M, A, N, and V (R, O, C, K, M, A, N, and 5 in Japan). Each one is in a different Robot Master stage. When the player get all of them, Beat becomes available. Those plates are used as a signal that allows Beat locate Mega Man. Beat can assist Mega Man in Proto Man's Castle and the Wily Castle; notably, against all four Dark Men, and the Wily Capsule.

Mega Man 6
There's four plates to collect: B, E, A and T. Those plates are gained after defeating Tomahawk Man, Yamato Man, Knight Man and Centaur Man passing through the correct doors.

Mega Man 7
There are still four plates to collect: R, U, S, and H. Like Mega Man 5, each plate is in one of the first four stages. When Mega Man collect all of them, he will gain Rush's Super Adapter function.

Mega Man IV
There are 8 plates: B, E, A, and T are in the first four stages, and collecting them allows Mega Man to use Beat as before. W, I, L, and Y are in the second four stages, and they are required to access Dr. Wily's room.

Other media
The plates appeared in the Rockman manga series. In the Rockman 5 manga, Mega Man collected the O and N plates without knowing their purpose, which is later explained by Dr. Cossack. Mega Man gathers the remaining plates and is able to call Beat. He also collects plates in the Rockman 6 and Rockman 7 manga.

In the Rockman 7 manga, Mega Man finds three plates before facing the boss. Junk Man taunts Mega Man by showing him the Rush Jet item and the last plate before hiding them in his domain. Mega Man finds the Rush Jet item when looking for Junk Man, but as Junk Man perishes without telling the location of the S plate, Mega Man must search it in the area.

In one of the shorts from Rockman 4Koma Dai Koushin, Mega Man collected the four Beat Plates in Mega Man 6 and tries to call Beat, but as he doesn't appear, Mega Man realizes that one of the plates is actually a "ヨ" instead of "E".