The Mamodo world was once the Pokémon world.A really long time ago that is. After the humans in their world went extinct the pokémon slowly evolved into mamodo over millions of years. Zatch is a direct descendent of Ash's Pikachu.
Dr. Riddles has (or had) the Answer-Talker AbilityIn his first appearance, while claiming to "know everything" his eyes were identical to Duford and Kiyo.
King Bell used the King's Privilege to erase GorenGoren was only mentioned in passing during the Zophis Arc, being the source of turning well over half (probably around 70) of the hundred mamodo in the previous battle. He was also probably that game's Big Bad as Clear Note was to Zatch. Since they didn't have a way to bring back or restore the left over demons BEFORE the next battle (which Goren probably gloated about), King Bell used the privilege on at least him after he won the crown. Even if Baou Zakeruga does eat up his hatred, it would never excuse the pain and isolation those children faced.
Both Apollo and Sunbeam had Answer-Talker Ability or different versions of itApollo was able to predict actions pretty much like Dufaux did but he was beaten by him which means that his ability was never even close as developed as Dufaux's one. Sunbeam in the other hand had an ability to look into other person's hearts and to communicate with them which was proven also to be one of the abilities of Answer Talker. Kiyomaro was able to do this in the last battle with Clear Note by giving commands directly to Sherry and Brago without saying anything
Maruss was brainwashed by Zofis or had a 2nd personality like Kolulu hadZofis was proven to be able to brainwash both humans and demons by changing their emotions or by strengthening their emotions of anger and hatred. By these actions he was able to go as far as to create a completely different personality to other demons. As we knew Koko was very kind before meeting Zofis. But after meeting him she completely changed and had a completely different personality. Also we know nothing about his actions before pretending to be Lord and gathering 1000 years old army of Demons. He could easily entertain himself by manipulating emotions of other demons. The same one goes with Kolulu. She was also very kind but after using the spell she revealed a different personality withing herself which triggered her to fight. Probably this different personality wasn't created by Zofis but was withing Maruss from the very beginning. Maruss was very kind to Tio in the Demon world. But when he was in need to fight (similar to Kolulu) he suddenly changed.
Clear Note wasn't really evilHe was just possessed by his ultimate spell. This happened at least three times earlier. The first one was Kolulu who attained a different personality by using a spell which cared only about destruction and winning the tournament. The second one was Riou. By using his ultimate spell he went into the complete berserk form similar to Kolulu. The third one was Gash himself. By using the advanced Baou Zakeruga he was overwhelmed by its power and was forced to hate and destroy. He was also the only one of three who was able to surpass the power of spell and retain his original personality. Unlike previous three it is possible that Clear Note's spell had a constant influence on him and he never acted by his own will.
King Bell used Baou Zakeruga to defeat FaudoIt was mentioned by Arth and Elly that Baou Zakeruga had some kind of relation to the ultimate threat called Faudo. The subject was never brought up again. So it is possible that Earth knew about King Bell's method of defeating Faudo. By knowing of his caution towards Baou it is also possible that he as well knew about its ability to devour the wielder if he wasn't strong enough. He could learn it only from the previous wielder of Baou - King Bell himself.