-Mr. (insert other name here)
If you don't like any of these names, you can always customize a name by picking a favorite word or the color of your betta, and translating it into a different language(use google translate if you need it).
Bettas enjoy pushing ping pong balls around the tank(make sure they are clean) and sometimes(make sure the marbles are too big where the betta will get stuck or too small in which they can choke) picking up marbles in their mouths and then spitting them out. The also enjoy live and silk plants immensely.
Good luck, and don't forget to upload pictures when you get him/her!