If I'm correct then Tailwind increases the Speed of all Pokémon on your team by **2x** for three turns, counting the turn you use it. This means that a Pokémon with a Speed value of 120 would have **240** Speed for the duration of Tailwind.

I want to give my Azumarill enough Speed EVs to out-prioritize BB from Talonflame with Aqua Jet under Tailwind.

- Azumarill's base Speed, with 31 IVs, 0 EVs and a neutral Nature is
**70**.
- Talonflame's base Speed, with 31 IVs, 252 EVs and a neutral Nature is
**178**.

Therefore, I need my Azumarill to reach a Speed stat that, when doubled by Tailwind, will reach at least **179** Speed. As this is not possible through doubling, he will need to reach **180**.

180 ÷ 2 = 90

I need Azumarill to reach a Speed stat of **90**.

Am I right?