Malaconda is a defensively oriented dark/grass type made by Smogon's Create a Pokemon project, or CAP. In the CAP, various Smogon users get together and create a Pokemon they think will make the metagame more balanced or interesting. Each Pokemon goes through a heavy review and production process, including the design of its art and sprites, its stats, its movepool and other notable elements. Typically, after much debate and review, the final product is programmed into Pokemon Showdown, and may be used in Random Battles or the CAP metagame.
On a side note, the etymology for Malaconda is Malevolent or Malice, as in evil, referring to it's dark typing, and Anaconda, the large snake of which it is based.