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, explosions, etc. 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 characters' universes, and are typically used as those characters' home stages. 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.

Stages range in size from the large ones, such as, to the small ones, such as WarioWare, Inc. Typically, stages involve a large central platform with ledges and one or more smaller platforms, as well as blast lines 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", because characters can walk off-screen and die without falling off of an edge first. Stages with walk off edges on both the left and right, like Peach's Castle, are sometimes called "walk off stages".

In SSF2, moving and transforming stages were introduced as this was a technical issue very hard to do in the first SSF. Galaxy Tours and Hylian Skies, for example, consists of transforming stages that change their own layout 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, 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 and enemies, such as lasers; local items such as pellets; and interactive objects such as Barrel Cannons.

An option called the hazard switch, featured in SSF2, allows players to switch off stage hazards and other stage changes.

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, 62 stages (not counting Galaxy Tours's sub-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:

Indeterminate stages
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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.