I saw this around 7-8 years ago on Toonami/Cartoon Network and I'm still not quite sure it was an anime or an animated TV show.
I watched this series completely in Spanish since that's my main language but sadly I was too young to remember anything else about the animation style or quotes from it.
The opening is the thing I'm less sure of but it basically recapped the story, and it was something like...
- a king having a belt (a belt? could be something else) that had elemental gems on it,
- the antagonist tried to get the gems so the king hid the gems all around the world, now the villain's trying to get it back and the heroes are trying to get them so the villain doesn't get them.
I remember 3 episodes, to an extent,
- The first was the heroes being trapped on quicksand, and they end up meeting with an old man and an old woman that save them, they spoke in gibberish and gave them food and a place to stay. Some of the protagonists were suspicious about this but were obviously told they were exaggerating. Eventually they found out the old people were speaking backwards and were trying to eat them, the old couple transform into monsters and they defeat them.
- Another episode is the heroes looking for the water gem and finding themselves on a beach with a huge castle floating right in the middle of the water. They tried their best to reach it (not sure how they did?) only to have one of them reach the castle and find a huge blue dragon with the gem on it's forehead.
- The next episode is just the rest of the characters getting to the castle and defeating the dragon.