Raising Attack or Lowering Defense?

Question

In any battle(in game or competitive) is it better to raise your Pokemon's Sp. Attack/Attack or lower your opponent's Sp. Defense/Defense? Why?

Answer 1

Damage Formula:

Let's say a Level 100 Normal Type Pokemon uses a 100 Base Power Fire typed move on an identical counterpart, both with 200 attack and defense.

Level is the level of the attacking Pokemon (100)
Attack and Defense are... well... (Sp) Attack of the attacking Pokemon and the (Sp) Defense of the attacking Pokemon. (200)
Base is the base power of the used attack. (100)
Modifier is a combination of STAB, Type Effectiveness, Random Damage, Critical Hits, Abilities, Held Items, etc. Formula. Let's just make this 1.

Now, what raised/lowered stat does more damage? Let's find out!

Attack:

For this, we're going to double attack to 400.

When we run it through the formula, we get 170 damage.

Defense:

For this, we're going to halve defense to 100.

When we run it through the formula, we get... 170 damage?

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Since both attacks do the same amount of damage, we can tell that it doesn't matter what stat is raised/lowered.

Answer 2

Its kind of the same if you think about it.
You raise your Attack/Sp.Attack, their defenses are less.
You lower their Defense/Sp.Defense, your attacks do more damage.

Answer 3

Raise your own, they can simply switch out and remove the bad stat affliction while raising your own lets you hit more Pokemon with the increased damage, although, with raising your own stat, only one Pokemon can take advantage.

Answer 4

Raise Attack.
If you lower the opponents defence and faint them, then the lowered defence is lost. but if you raise attack, then it stays with you even if you faint the opposing Pokémon.