His house is just left of the Pokemon centre in slateportcity.
The Day Care Centre is west of Mauville City.
There is a bike shop in Mauville, east of the Pokemon Centre. Talk to Rydel (the owner) and chosse your bike!
The white rock in Pokemon Emerald can be found outside the space centre in Mossdeep City. This rock seems to hold much significance to the people living in the area.
Fly to mossdeep city in Pokemon emerald version then go to the space centre there will be two proffessors one will say what 99%..... and one will say Rocket Launched Succesful No.__
your rival (May/Brendan) will give it to you if you will defeat him/her near the weather research centre. hope it helped.
In Mossdeep City which incidentally is also home to the Twin Gym Leaders (Psychic Type)
The city in which you get a bike is mauville city. to find the bike shop is really easy as all you have to do is go left of the Pokemon centre and there is a shop with bikes outside
If you're talking about on Diamond or Pearl you have to get the explorers kit from a man in Eterna City. His house is just to the right of the Pokemon Centre. As for Sapphire, Emerald and Ruby, you need a pokemon that knows Hidden Power.
In Pokémon Emerald, the sun stone is obtainable at the mossdeep space centre
steps
Upstairs in the Pokemon centre