Beat (ビート, Bīto) is the robotic bird companion of Mega Man next to Rush. He was built in by Dr. Cossack for Mega Man as a gift for saving his daughter Kalinka (though it was actually Proto Man the one who saved her). He serves a support role by either attacking enemies or protecting Mega Man, depending on the game.
In the Mega Man series
Beat first appeared in Mega Man 5 where he attacks enemies that appear in Mega Man's path including bosses, however, in order to obtain Beat, the player must collect 8 plates that spell the game's name (thus, the plates are M, E, G, A, M, A, N and 5) distributed all long the eight Robot Masters stages. Beat reprised exactly the same role of attacking enemies in Mega Man 6, this time, however, he could no longer attack bosses. Once again, plates were required to obtain him, with the difference this time only 4 plates were necessary (they spell his name: B, E, A and T).
Beat's most notable change came in Mega Man 7. After the player rescues him in a hidden area in Slash Man's stage using the weapon Scorch Wheel, Beat will appear whenever Mega Man falls into a pit and pull him for a while, but only if he previously had an item known as Beat's Whistle. The player, then, must move to a safe area before Beat releases Mega Man, as he can't hold his weight for much time. Beat did the same thing in Mega Man 9 and Mega Man 10, the item required to use him was renamed Beat Call, though.
In Super Smash Flash 2
Mega Man uses Beat Call in Super Smash Flash 2 as his up special move, with this, Mega Man pulls out Beat, giving him about three seconds' worth of flight, not so different as he did in the Mega Man games. There is a notable difference from the Mega Man games and SSF2; this move in can be used in conjunction with an uncharged Mega Buster while in the Mega Man games, one cannot attack at all.