user17981: I am looking for a Python chess engine package. It must be fully contained in Python, I don't want to download separate files for the engine itself and link them up somehow.
All I want it to be able to do is take a FEN and provide best move. It should obviously be a strong engine, at least 2500 rating.

user1025: An alternative to Sunfish is PyChess: http://pychess.org/ (or https://github.com/pychess/pychess)
It's stronger than sunfish (has 2100 bullet rating on lichess: https://lichess.org/@/PyChessBot ) and also allows playing chess variants, such as antichess or fisher random.
It has a lot more code than sunfish though, so pulling it out as a separate library takes a bit more work.
See also http://talkchess.com/forum3/viewtopic.php?t=67025

user825: I have experience with only SunFish, but I doubt it's 2500+ level.

http://talkchess.com/forum3/viewtopic.php?f=2&t=67025

This link should help you. If you're not happy with the folks at talkchess, you probably won't find a better answer anywhere else.

17981: <p>I am looking for a Python chess engine package. It must be fully contained in Python, I don't want to download separate files for the engine itself and link them up somehow.</p>

<p>All I want it to be able to do is take a FEN and provide best move. It should obviously be a strong engine, at least 2500 rating.</p>
 1025: <p>An alternative to Sunfish is PyChess: <a href="http://pychess.org/" rel="nofollow noreferrer">http://pychess.org/</a> (or <a href="https://github.com/pychess/pychess" rel="nofollow noreferrer">https://github.com/pychess/pychess</a>)</p>

<p>It's stronger than sunfish (has 2100 bullet rating on lichess: <a href="https://lichess.org/@/PyChessBot" rel="nofollow noreferrer">https://lichess.org/@/PyChessBot</a> ) and also allows playing chess variants, such as antichess or fisher random.</p>

<p>It has a lot more code than sunfish though, so pulling it out as a separate library takes a bit more work.
See also <a href="http://talkchess.com/forum3/viewtopic.php?t=67025" rel="nofollow noreferrer">http://talkchess.com/forum3/viewtopic.php?t=67025</a></p>
 825: <p>I have experience with only SunFish, but I doubt it's 2500+ level.</p>

<blockquote>
  <p><a href="http://talkchess.com/forum3/viewtopic.php?f=2&amp;t=67025" rel="nofollow noreferrer">http://talkchess.com/forum3/viewtopic.php?f=2&amp;t=67025</a></p>
</blockquote>

<p>This link should help you. If you're not happy with the folks at talkchess, you probably won't find a better answer anywhere else.</p>
