So here is a screenshot of UI in action for Player vs. Player combat. The points made here is that people should have an open Ui feel, as in pvp you not only need to see whats going on with movements but utilities as well (ie. cooldowns, groupings, spells, crowd controls). The following is my set up, not required but an example or template.

Addons:

UnitFramesImproved : helps better show hp/resource bar and provides an easier vision on information while remaining light weight

Tidyplates : changes appearance of name plates - benefits in the watch of CC, dots/hots, health and overall vision. 

ExtraCD : displays internal CDs procs/cooldowns, necessary to get the most out of abilities and damage/pressure at all points, also helpful when wanting to time up personal burst thus making random burst mechanics become controlled

Battlegroundtargets : required for rbgs - displays enemy team, names, clickable targeting/focus setting. also shown are the setting required that be turned on or will be on my screen, how many are targeting an enemy, class-spec, active health movement.

(goal is to reduce the stress put on RAM, while the addons pull seperately from RAM, they do slow input lag, so while i say this not bashing current users but Elvui/Tukui are not as desirable as they triple take from game and can cause more issues because unlike dragons - players ping differently to eachother across servers)

Optional addons:

Platebuffs : will be required once patched for 6.0+

gladiatorlossa : pvp/spell announcement system, heavily recommended but not required - no set up needed!

interruptbar : desirable for casters to keep track of cc, kicks, and blankets

Bartender/dominoes : action bar addon helps for clearing up screen as well as bindings, highly recommended if not used to/skilled with blizzard LUA or binding

Capping : timers on nodes and resets for bgs