From the Super Mario Wiki
Brinstar is one of the main areas on Planet Zebes in the Metroid series, of which Samus Aran is the main character. It appears as as an acid-filled stage in Super Smash Bros. Melee. A Chozo Statue would rise to life occasionally in Brinstar. A related level is Brinstar Depths. The stage reappears in Super Smash Bros. Brawl as a Past Stage.
It also appears in Adventure Mode, where the player must battle Samus. After the battle, the planet begins to self-destruct, and the player must escape by jumping on the platforms above.
The only real gimmick is the acid, which occasionally rises up and burns any players who do not get to higher ground, with the top platform being the only one that never sinks. The acid can sometimes save the player if he or she falls, because it sends them flying straight back onto the field; however, sometimes it is so low that a player will still fall to his defeat. Also, underneath the two side platforms is a bit of sticky substance. If it is hit enough, it snaps, causing the platform to tilt, making it dangerous to walk on. Another example of this is the "bacteria" in the middle of the stage. This needs consecutive attacks and, when broken, splits the whole stage in two, making a dangerous gap for players to fall in.