You're right

Don't make my mistake and get fooled with language SQL not plpgsql. I literally thought it has to be function with single select statement (like inline functions) because other way I got error that the function doesn't exist.

In general the rules of defining levels:
let employee of id = n have level m.
Then we look for the employee whose manager's id is n and assign him level (m + 1).
I don't think that's any kind of spoiler. Hope it clarifies the kata which is really cool.

The simple fact that typical insert/update/delete commands aren't enough is an argument yoou need some wider knowledge and looking for it is a waste of time. If You want to copy/paste the solution - ok, it's not college, you don't get certificate for completing katas, however if you're doing exercises (eg. katas) and want to master your skills, you have to have those skills first and get fluent with them by comming up with solutions. So hints would be cool. However - it's Your kata (and it's cool it is here), so You're the boss.

I have no idea what am I doing wrong. I display two tables in two distinct SELECT statements:
first with three columns name, won, lost, where each name has total sum of wins and losses (minus forbidden kicks);
second ordered by total wins only top six.
As I test it I get the info that the output doesn't have three columns. What's the matter? Do I understand the instructions wrong?

@edit: Kata doesn't allow creating new tables - You have to display the 'fighters' table with appropriate conditions.