Whats in the under water temles at the dive spots.is there apokemon.what..

I believe you are talking about the Abyssal Ruins. There isn't a Pokemon at the end of it. There are just many items throughout the Four Floors of the Ruins.

I bet you can find a Video on the Abyssal Ruins either Here or on Youtube.

Hope this helps!

There isn't really a way of knowing what those symbols mean. But it is possible to decifer it. Here's what it means.
Listen to King's words.
Primes lead to truth.
King is brave.
King never loses hope.
King is kind.
King has a dream.
King is adventurous.
King accepts all.
King turns 2nd corner.
King turns 3rd corner.
King turns 5th corner.
King turns 7th corner.
Have the heart of King.
Here we praise King.
King's light shines.
King moves his people.
King acts with love.
King fought hatred.
No king gets lost.
Go on, brave king.

Life is gratitude.
Eating is receiving life.
Good or evil isn't all.
Do not be barbaric.
One must not waste.
All is precious.
Wars create tears.

King talks to all beings.
Saved all from waves.
King is hope for all.
Think act with love.

King defeated ③ alone.
④ joined King in a day.
King called ⑤ beings.
King is hope and future.
The great King ⑥.

When I tried deciphering it, the last stanza seemed to have numbers where you have to plug in a Pokemon or something. I know it's kind of weird.
That doesn't really help so I'll tell you what it's for. You need the language and board to get to the next floor. There are four floors in Abyssal ruins. Each containing various treasures. A maniac in Undella town will buy these treasures. On the last floor of Abyssal ruins there is a Relic Crown and the maniac will pay you 300 000$ for it.
(The maniac is in the Riche's house to the left.)