Each of the following paragraphs refer to one of the four "gods" :
I am thunder, especially if your tongue miss a bit,
No marshal can stop me, they just make me stronger
You want to take me for an exhibit?
Fine, but be ready to spit fire
I am a jewel, a shiny pearl
But once you come close to me, you'll see we're many
Unlike my brother, i'm not here to howl
And despite beeing clean, China will crush any
I am depth, torn between my two brothers
Shall I cry? Shall I smash?
Most think they don't notice my power
One slap, and I shine like a flash.
I am emotions, joy sadness hate
Often a regret when used in the shower
I'm here to make you fascinate
But remember, all four are stronger together.
Who are the four gods and what is the entity when they're together?
First hint :
adding a certain existing tag would have make it too easy