Question

Can a Pokemon die or not?
In the anime, manga or games.
Just explain.
Pokemon is great.

Answer 1

This is mostly an opinion based question, but I'll say what I think happens to Pokemon. When Pokémon are defeated in battle, they 'faint'. You then take them to the Pokemon Center, where they are healed back to 'perfect health'. However, there are a few things that prove that Pokémon can die (imo).

Lavender Town

In Lavender Town, there is a tall building, where 'the spirits of departed Pokemon rest'. Essentially it is where dead Pokémon are buried. By speaking to the many characters in this tower, you can find proof that Pokemon do die. For example, if you speak to a blonde girl she will say, "Oh my poor Pokémon, why did you have to die?" Or something along those lines.

Gary's Raticate

There is a theory regarding your Rival Gary's Raticate, however it is a theory and therefore may not be true.
At the beginning of Pokemon Red, Blue, Green, FR, and LG, you are introduced to your Rival, Gary. As your rival, he proceeds to battle you multiple times in the game. In Gary's team there is a Rattata, which later evolves into Raticate. However, when you reach Lavender Town, and go to the Tower, you find Gary standin at one of the gravestones. He then proceeds to battle you, but this time Raticate is not on his team. The theory implies that YOU killed his Raticate, and that when Gary got to the Pokemon Center it was too late. His Raticate had died.

Giratina and the Sky Warrior

This is just one example of Pokémon 'dying' in the anime/ films. In one scene from Giratina and the Sky Warrior, Giratina appears to be dying. However, it gets revived by Shaymin's Aromatherapy.

Answer 2

Yes, and there are lots of examples of this. here are some of them:
lavender town, it has a cemetery for Pokemon meaning they are buried there and have to be dead. Gary's raticate, Gary talks about loosing a Pokemon, when you battle him, he doesn't have raticate. Mt pyre, Pokemon emeralds Pokemon cemetery, a girl even says see misses her skitty suggesting it died. Pokemon fire red and leaf green, you can find someone standing by the grave of his onix. Spoink dies if it stops bouncing, if it faints it can't bounce and dies. In the manga, lots of Pokemon die. In the wild they die or they would overpopulate the world. Some Pokemon hunt other Pokemon for food. Where does mandibuzz get its bone nest and covering from. It says absol can live for 100 years, and ninetales 1000, after that, they die. Some Pokemon come from spirits of other Pokemon. Cubone wears the skull of it's dead mother, meaning it's mother died.

Lots of Pokemon die, and there are many examples of this.

Hope I helped.