no
Mirage island
it is a item you can put in your secret base
In those indents, if you have a Pokemon that knows the move secret power, you can make your own secret location and decorate it.
Not really, but there is one to sky pillar
you must be getting it messed up with Pokemon ruby version. there is no secret slab in Pokemon mystery dungeon. at least in red or blue.
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.
secret power
In one of the southern tree houses of Fortree City.
hes not in platinum:( try ruby
in Pokemon diamond and pearl just go on your udventure and you will find it but in Pokemon sapphire,ruby it's hard to get it
The Ruby Is In Mt.Ember And The Sapphire Is In The Team Rocket Secret HideOut (Dotted Hole)