~ NETPLAY ~
smashladder.com/help/netplay-guides
Guides that can help you set up Netplay for Melee and Project M, allowing you to play those games with other people online.

For SSB64, refer to this guide:
pastebin.com/ZskFfXnu

~ ROSTER MAKER ~
apps.warchamp7.com/smash/rosterHD
A site that can be used to show off your mains.

~ 64 ~
> 19XXTE
A hack of 64 which implements a variety of competitive features without the use of codes.
Get it here: smashboards.com/threads/19xxte-ssb64-rom-hack-updated-6-30-2015.402248

~ MELEE ~
docs.google.com/document/d/1_6o5NHvI9P8-qHp2M8w1gDzL_-JNonEE81Mh4ulY1PY
A document meant to help beginners out with Melee, and by extension, Project M.

> SD Remix
A mod of Melee meant to rebalance the game.
Get it here: sdremix.com

> 20XX
A hack to be used to help you hone your Melee skills.
Get it here: smashboards.com/threads/the-20xx-melee-training-hack-pack-3-02-update-pal-chars-more-alt-stages-costumes-new-debug-menu.351221

~ BRAWL ~
These are mods that take the base game of Brawl and change it up to be a much different and generally better experience. You will likely need a 2 GB SD Card for these to work. More detail about that is given on each site's download pages.

> Project M
The most popular of all Brawl mods, aiming to recreate a fast experience like Melee was.
Get it here: projectmgame.com

> Balanced Brawl
A Brawl mod that tries to balance the cast of Brawl but also tries to keep the core physics and mechanics of Brawl rather than change them to be faster.
Get it here: balancedbrawl.net

> Brawl Minus
A Brawl mod that aims to make every character broken.
Get it here: brawlminus.net

~ FOR 3DS/WII U ~
Comparison:
ssbwiki.com/Cross-platform_comparison_of_Super_Smash_Bros._4
This link outlines the differences and similarities between the two versions.

Media:
mega.co.nz/#!c5olzLxT!nHY8AelJjceDyQHbpoSQcXcefVlEDRPt2FGWBbKrAaU
A rip of the Wii U OST. Contains every song except 3DS exclusives.

smashbros-miiverse.com/music
You can also listen to specific, individual tracks, sorted by series.

smashbros.com/us/movielist
Various videos, including Character Reveal trailers, Commercials, and Directs.

~ /ssbg/ ~
For 3DS/Wii U Character Primers:
pastebin.com/5ryn1CkP
A collection of character guides written by /ssbg/ goers. Mostly outdated compared to Smashboards guides, but you might learn something.

Tournament Guide:
pastebin.com/ACSy6nc4
A frequently updated list of tournaments regularly held by /ssbg/.