This is a company event only, just using the hype of making the event look like The International, no copyright infringement intended.
Here are the participating teams and their rosters.
To make the tournament more exciting and dynamic, the roster is shuffled according to their respective MMRs’. Each team has high and low-level MMRs’ so that each match will not be one-sided matches.
This tournament is also a way for the company to bound other employees and makes a friendship out of the likes of the employee, which is Dota2.