Are you sure that you have OpenAL installed?
Crash log specifically mentions that one of the game's files is being used elsewhere. Be sure to close any text editor/other copies of the game before starting it up.
This type of bug should be posted in the general Bugs forum.
You likely forgot to install the software requirements for the game: OpenAL and .NET Framework. Without them, the game will crash before the title screen appears.
What you experienced is almost certainly the result of the ghosting bug; the Pokémon that follow other players have a small chance of randomly appearing elsewhere on your end. This won't happen if you play locally.
The UpToDown files were not provided by the developer team and are potentially malicious. We do not provide support for them, so use them with caution. If you're looking for an old version that we do support, you should be able to find Indev 0.53.3 on the bottom of the GitHub releases page.
If it worked before on the same computer, but now it's no longer working, there's very little I can think of that would help. Restating your computer probably won't do much, but it wouldn't hurt to try. Maybe your graphic drivers need to be updated?
Aside from direct downloads, there could be things in the Roaming folder under Kolben Games and P3D Team.
Language as in display (English, Spanish, etc.), there are a few languages with unsupported characters that cause a crash (most notably Turkish).