Speed Priority

[NovaHorus]

What is it? Check attack dex.

 

[Xinkc]

it means when the attack is going to be used, like how quick attack or extreme speed always attack first and how counter and mirror coat are always last

 

[NovaHorus]

Whirlwind's is 250. Agian what does that mean?

 

[Horn Drill]

Whirlwind's is 250. Agian what does that mean?

It means that Whirlwind/Roar will always go last except for when they're used on the same turn as Focus Punch, if I'm not mistaken.

 

[Pokedexter]

quick attack, aerial ace and mach punch are 1

 

[The guy from Pireas]

it means when the attack is going to be used, like how quick attack or extreme speed always attack first and how counter and mirror coat are always last

Yep you are right...