Pokécharms

Absolutely not - you're not allowed to use TCM assets anywhere other than the TCM itself - and I know the chap who made the Amie backgrounds absolutely didn't give his permission for anyone else to use them other than as part of the TCM.

Basically, I'm afraid to say that using that background is stealing, so you'll have to recreate that Undertale card with your own background

Oh, ok, thanks anyway!

Just to know, what kind of thing can I upload and what kind of things I can´t?

Well, it says in the rules. Short answer, you have to have made it entirely yourself. You can use bases, but they have to be linked to in your description and be explicitly marked as free to use (that is, the base artist has to have said anyone can use it when they posted it)

Does that means if I post my own character that I made here:

http://hapuriainen.deviantart.com/art/Pokemon-trainer-Creator-v-2-257074027

It´s okay?

No, because that's a generator. You're just sticking other people's work together, so it doesn't count as you making it.

ok! thanks!