In one of the southern tree houses of Fortree City.
it is a item you can put in your secret base
Unfortunately there is no TV in Ruby/Sapphire/Emerald for a secret base. Many people worldwide will be upset. :(
No
To find your Secret Base, talk to the short guy in a house in western Mosdeep City. He will mention a base on a certain route. Go there, and find your Secret Base on that same route!
In Pokemon Ruby, the time changes do not affect which Pokemon can be caught. The time changes affect day-to-day things, which is basically challenging someone else in their secret base.
you go to lilycove deparmemt store top floor
no, you use secret power on it then it makes a base.
You go to their secret base just tright of lilycove
Go to the shopping tower in lillycove city
Those are places you can make your secret base in how to do that you say use secret power on the indents to make a hole appear now you can create your own secret base.
If you mix records with your friends and they have Lv100's you can raise your pokemon's level by visiting your friends in their bases and battle.
Nothing really, just some fun and the chance to decorate your own room.