Is shininess of a Pokemon have effect to EV growing?

Question

I found my shiny haxorus (from natural preserve) have a unusual stats after I train her.
She holds power braclet and defeat purrlion, but her atk stats not grow.

Answer 1

Evs. Ah, here we go. EVs are determined by the Pokemon you fight. I believe Purrloin gives out 1 Attack EV, and every 4 make another stat point.

Ex: You fight 4 Purrloin, then level up. You get another Atk point!

However, You have the power bracer.

That means, if you fight 4 Purrloin, each one gives you 5 Atk EVs, so you would have 20 Atk Evs, so once you level up, you get 5 Atk points!

Comments

I believe Purrloin gives out 1 Speed EV. But otherwise this is correct. So when you knock out a Purrloin with the power bracer, it will gain 1 Speed EV and 4 Attack EV's.

Answer 2

No. Shininess does nothing to the Pokemon's growth. The reason your Haxorus' stats are not increasing is likely because you are following the 252/4 EV rule; this is not so if you are not LV 100; the number for a stat increase is a bit larger (see this). Nothing has happened to Haxorus; nor does it being Shiny effect it's growth.

You are likely expecting too much of an increase in too little time; you require patience to increase the stat.

Further reading: http://bulbapedia.bulbagarden.net/wiki/Effort_values