Click on this link to know more about natures:
https://pokemondb.net/mechanics/natures
Click on this to know more about effort values:-
https://www.google.co.in/url?sa=t&source=web&rct=j&url=https://bulbapedia.bulbagarden.net/wiki/List_of_Pok%25C3%25A9mon_by_effort_value_yield&ved=2ahUKEwiG2bDfusjYAhUFmZQKHfqlCGAQFjACegQICRAD&usg=AOvVaw1J9QGUiGvAikmISaIor9pE
Click on this link to know about EV training hotspots:-
https://www.google.co.in/url?sa=t&source=web&rct=j&url=https://pokemonrevolution.net/forum/viewtopic.php%3Ft%3D12825&ved=2ahUKEwjz2MmHu8jYAhVGkJQKHVZgBgwQFjANegQIARAB&usg=AOvVaw2DoL81ZeLvU7i3kSdLRbaq
There is no cool down for E4. I am not sure about this, but I think you should train defense for tank Pokemons. Good luck mate :)
Hey! All the Pokemons you had before will be locked before going to Johto. This also applies to all of the regions. For examples, when you are going to Hoenn, the pokemons you had while got from Kanto and Johto will be locked.
Actually, that's not the right computer. The correct computer is the one in B3F. It is one of the computers of the 8 desks in B3F. You have to find the computer with the picture of Admin Christina in it. Here is an image:
Good luck
Welcome to PRO. My suggestion is not to evolve pokemons early, as you will have to suffer. But at the end of the day, it's your choice. Good luck :Smile: