Stage

A stage is the designated area where characters fight each other in the  series. Each stage has a different layout, size and shape, sometimes including hazards that affect the matches in some way, such as lava, water, or explosions. The word "stage" usually refers to a Group stage, but can also refer to the ground or large central platform within this location. Some stages, such as those in the various Stadium modes, exist for purposes other than fighting.

Group stages
In both Super Smash Flash and Super Smash Flash 2, most of the versus mode stages are available from the start, while a small number must be unlocked by completing certain objectives. Most stages are derived from places in the playable character's universe, and are typically used as that character's home stage. There are some stages with no character representatives, such as Battlefield and Final Destination; additionally, not every character has a stage from their own universe.

All stages range in size, from large, such as, to small, such as WarioWare, Inc. Typically, stages involve a large central platform with ledges, along with one or more smaller platforms above the main stage. Blast lines are placed above, below and to the sides of the visible area. Some stages have floors that continue past the edge of the visible area and pass through a side blast line. These floors are known as "walk-off edges" or "walk-offs", as characters can walk off-screen and KO themselves without falling off of an edge first. Stages with walk-off edges on both the left and right, such as Peach's Castle, are sometimes called "walk-off stages."

In SSF2, moving and transforming stages were introduced, as this was a technical issue in Super Smash Flash. Galaxy Tours and Hylian Skies, for example, are transforming stages that change their own layouts to add new stage possibilities. Most of them possess a default layout known as a "main hub", which the stage returns to after every transformation ends. Notably, Silph Co. is one of the few that does not have a main hub, instead cycling through twelve different layouts in sequence.

Other stage elements include breakable barriers and platforms, such as the wood planks of Emerald Cave or the sloped floor of Green Hill Zone, stage hazards, such as the Blocks and Bombs on Bomb Factory, local items, such as pellets, and interactive objects, such as the Barrel Cannons on Jungle Hijinx.

An option called the hazard switch, featured in SSF2, allows players to switch off stage hazards and other stage changes, streamlining gameplay for a more competitive experience.

In Super Smash Flash
Most likely because of limitations, the original Super Smash Flash features only eight versus stages, of which six are starter and two are unlockable (those with shaded cells):

In Super Smash Flash 2
Based on the demo versions, 67 stages are confirmed for Super Smash Flash 2 and will be appearing as starter stages, in addition to unlockable stages. Of these stages, 17 are designated as past stages, which are based on stages from the official  series in both name and layout. The currently confirmed stages are as such:

Removed stages
In Arena, there is a special rectangular-enclosed stage with goals located on each end of the stage that serves specifically as the setting for Sandbag Soccer. Another similar stage exists as the setting for Sandbag Basketball, but with minor changes and a different background.

Solo stages
In Solo, a number of stages appear that are not available in Group mode. Stages found in Adventure mode are also be referred to as levels.