Hi, I don't know much about this event.  Was this just for special people Nintendo directly invited.  Or was there reginal events some where that people could play in to make it to the competion at E3 this year?

They were invited by Nintendo.

https://e3.nintendo.com/tournamen...

Thanks for the info.  I'm really hoping Nintendo will do another event like the Nintendo Wolrd Championships 2015 and 2017.  I guess this does not count since one had to be invited to play.