Coliseum

Coliseum is a stage appearing in Super Smash Bros. for Wii U which is based on The Arena from multiple games in the Fire Emblem series. It is a stage of large size with no real hazard present. There is machinery underneath the stage which activates variable platforms which are currently unknown.

Origin
Although this stage is named Coliseum, in the Fire Emblem series it is known as The Arena.