So can someone explain how the whole region restriction works? like if u catch a pokemon in kanto you cant use it in johto or trade them in another region??

also will i be able to have a pvp team with pokemon from different regions...?

As long as you play the kanto story, you can obviously only catch pokemon from kanto. Furthermore you cant get Pokemon from Jotho through trades as long as you play the Kanto story (8 badges + elite Four). Once you go into Jotho all your kanto pokemon get locked and you can only use Pokemon from Jotho. Furthermore you cant get or use new Pokemon from Kanto even through trade as long as you play the Jotho Story (8 badges). As soon as you got the 8th badge from Jotho you can use Kanto AND Jotho pokemon without any restrictions. Even in pvp

Yep, that's correct. Get all badges in order to unlock them, you can also visit Kanto again as soon as you've got the 8th badge of Johto.

-Moved to proper place--