[Helpme]

https://www.pokemonpets.com/Shiny-Mega-D...edex-10719

Shiny mega diance is not a common pokemon seen in ELO or PVP and for good reason. Although it has really high base stats (at least 137) there is one glaring problem with this pokemon and that is its base 62 HP stat. 

Its abilities are Fairy Master, Maximum Guard and Shield Master. Fairy master increases the base power of its moves by 40%, Maximum Guard prevents its stats from being reduced and shield master decreases base power of opponents moves by 30%

Role: Special attacker 

Diance is good at countering specific stat reducing pokemon (like shiny mega umbreon for example) and being good against dark types and fighting types.

Best Items: 

Survival armor (trust me you'll need this) , special attacking weapon and Epic hammer

Best Nature(s): 

Modest, Mild, Rash, Timid 

Recommended moveset: 

Moonblast, Power Gem/psychic, Substitute/protect, Earthpower/After you 

This moveset relies on using survival armor to live one attack, boost your stats then attempt to sweep your opponent. Key word being attempt...

Role:Skill Swapper

Best Items: Survival armor, Rock orb/Fairy Orb

Best Nature(s):Modest, Timid 

Recommended moveset: Skill swap, Moonblast, Safe guard/Protect/substitute, Power gem 

Diance can skill swap its so-so abilities with an opposing pokemon that has perfect body and expert regenerator abilities thus giving it more reliability. This can also help to status induce (if you have an inducer on your team).

Role: Physical attacker 

Best Items: Survival armor, Attack weapon, Razor claw  

Best Nature(s):Adamant, jolly, Hasty, Naive 

Recommended moveset: Diamond storm/stone edge/rocktomb/rockslide, Flail, Secret power, Return 

This set ignores the fairy master ability and and relies on diance's 200 base attack which is equal to its special attack to surprise the opponent. It's physical movepool is not wide and it does not a have a physical fairy move to abuse Fairy master ability. 

Diance can do other things like reduce opponents stats or boosts its own stats to help team synergy or it can inflict status, these are not effective roles in my opinion as such i won't cover them. 

[Reem]

Great