Let's compile any resources and guides for Pokémon Uranium in this thread. Listing them all here makes them easy to find and use.
* An installer that can be used when the servers are down.
* Main bug report thread.
* A form you can fill out to report bugs.
* Pokéradar guide for finding Hidden Ability Pokémon in Uranium.
* Explanation of what Online ID is and how it's different from Trainer ID.
* Explanations for many core mechanics of Pokémon breeding and raising. Much less wordy than Bulbapedia's articles.
* Pokémon Uranium egg group chart.
* Discord chat for serious Pokémon Uranium breeders.
* List of move tutor moves. (Has the bug where some moves cannot be learned been fixed?)
* Listing of all current GTS trades
What others don't I have here? Let me know.
General resources
* Pokémon Uranium subreddit for general discussion.
* Item location walkthrough. (Mostly correct, slightly out of date)
Walkthroughs
* Basic story walkthrough. (Mostly correct, slightly out of date)* Item location walkthrough. (Mostly correct, slightly out of date)
Installation, patching and bug reports
* How to apply the official patch.* An installer that can be used when the servers are down.
* Main bug report thread.
* A form you can fill out to report bugs.
Gameplay mechanics
* Bulbapedia has information on the main games' mechanics, most of which are valid in Uranium. (Uranium follows the same rules as generation 6.) It has thorough articles on mechanics such as Hidden Abilities, Individual Values, Effort Values, Natures, Egg Moves, Egg Groups, and Pokérus. Articles are so detailed that they may be overwhelming; Youko's breeding guide covers many of these things in a simpler format.* Pokéradar guide for finding Hidden Ability Pokémon in Uranium.
* Explanation of what Online ID is and how it's different from Trainer ID.
Breeding
* Youko's breeding guide. Note that a few parts of it, such as its section on how to find hidden abilities, are outdated.* Explanations for many core mechanics of Pokémon breeding and raising. Much less wordy than Bulbapedia's articles.
* Pokémon Uranium egg group chart.
* Discord chat for serious Pokémon Uranium breeders.
Other
* Locations of all TMs and HMs.* List of move tutor moves. (Has the bug where some moves cannot be learned been fixed?)
* Listing of all current GTS trades
What others don't I have here? Let me know.