Question about the Huge Power Ability

[Greninjaman]

Could someone explain to me how Huge Power works? I am watching a video and the person got a Marill and was excited to see that it has Huge Power. I am aware that it boosts attack, but what does it do? Does it boost the base attack stat of the Pokémon or what? How does this affect the Marill (or any Pokemon with the ability)?

 

[StormyStinger]

From the bulbapedia page:

Huge Power doubles the Attack stat of the Pokémon with this Ability.

Because it is an Attack modifier and not a stat stage change, it will double the user's effective Attack stat when using Foul Play or Body Press.

 

[Greninjaman]

From the bulbapedia page:

So if say mew were to have huge power, it would have 200 attack instead of 100?

 

[StormyStinger]

As far as I can tell from a quick browser search, it also seems that not only doubles the base stat, but other stat boosts such as EVs.

 

[dig]

So if say mew were to have huge power, it would have 200 attack instead of 100?

It boosts the final result of your attack stat, so when calculating, it will go with base stat, IVs, EVs then any attack buffs.

An Adamant Mew with
100 Base ATK
Huge Power
max IVs & EVs

is the same as an Adamant Mew with any other ability, but with 248 as it's base attack, so very close to a 2.5 boost, at the end of calculation.

If both Mews have no EVs, then a 100 Base attack with Huge Power is equivalent to 218.
Remove IVs & EVs, that becomes 100 versus 203
Give both a neutral nature, it's 100 versus 202.