https://www.ministryofdefense.net/stepping-into-the-arena-guide-directory/ Collection of guides for rated PVP in World of Warcraft
https://www.icy-veins.com/wow/pvp-class-guides Detailed guides for each class and spec
http://www.skill-capped.com/app.php/macros/ Macro suggestions
http://www.wowhead.com/guide=1413/battlegrounds-101:-honor-made-easy A very detailed guide on the different battlegrounds and some pretty solid strategies on each
https://www.wowhead.com/beginners-guide-to-wow-pvp-and-arena Very detailed and in depth. Highly highly recommend.
https://www.worldofwargraphs.com/pvp-stats/classes PvP statistics for your character, team, and more
~REQUIRED~ https://www.curseforge.com/wow/addons/reporter-battleground-map Shows capping times and where everyone is
https://www.curseforge.com/wow/addons/dontcast Tells you when your target has a strong defensive on that will block your attack/heal them from your attack
https://www.curseforge.com/wow/addons/h-h-t-d Clearly shows a player that is giving strong heals to their allies and theirselves
https://www.curseforge.com/wow/addons/battlegroundenemies Shows buffs, debuffs, trinket status, and more.
https://www.curseforge.com/wow/addons/gladius Adds enemy unit frames to arenas for easier targeting and focusing.
https://www.curseforge.com/wow/addons/gladiatorlossa2 Announces the usage of crucial abilities cast by your opponents