can anyone say me how to create a clan, what are the requirements, what are its advantages, how is it benefitial for the owner and the user?

Your Clan <-- there you can create a clan, you just need 9950 coins (if I'm not wrong).
idk what's the benefits, but 1 thing I know, you'll gain more experience become a leader.
In Clan, you can get some pokes that you won't get in maps, like golett/evo, frillish/evo, etc. Also you can get coins from clan credits