How much extra strength is an attack given if it is your pokemon's type?

Question

I believe that I was once informed that if you are using a move that is the same type as your pokemon, it is stronger. (Ex: Vaporeon using surf (special attack, power 95) is stronger than Vaporeon using ice beam (special attack, power 95). If anyone could verify this, I would apriciate it. If it is true, how much does it improve the move? Thank you.

Answer 1

What you are talking about is STAB (Same Type Attack Bonus)
With STAB you get a 1.5 multiplier.

If you still don't get it try reading this.
http://www.serebii.net/games/damage.shtml

Comments

There's also an explanation here: http://pokemondb.net/type

Answer 2

It is 1.5% the normal damage but I think Ice beam is stronger than surf because it also has a 10% chance of freezing which I find very useful.

Comments

That's a real small percentage, and freeze usually doesn't even work most of the time.

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It's not 1.5% the damage. It is multiplied by 1.5, just like it is in the mystery dungeon games.

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1.5% lol