No the Pokémon Ruby and Pokémon Sapphire version of the Mirage Island is not in Pokémon Omega Ruby and Pokémon Alpha Sapphire however they made their own different variations of the Mirage Island concept but this time by creating more mirage islands that can appear at any time in the water routes or in the sky.
In the Hoenn Pokedex in Pokemon Omega Ruby and Alpha Sapphire, these are the Electric-type Pokemon you can capture in the wild (These exclude ones from the National Dex): Electrike, Plusle, Minun, Magnemite, Voltorb, Electrode, Pikachu, Chinchou, and Lanturn. By using the Dexnav, you can find Joltik and Luxio. On Mirage Island, you can find Zebstrika, and Elekid in Mirage Mountain. The legendary Pokemon Raikou can also be available for capture, which appear as a Mirage Spot between 0 minutes and 20 minutes of an hour. For example, it can appear at 1:15 pm/am, since it is between 0 and 20 minutes.
In Pokemon Omega Ruby, Latios can be found in Southern Island after obtaining the HM Surf and going to Route 123. To find Latias, you will need to get the Eon Ticket to fly to Southern Island to get her. Pokemon Alpha Sapphire has the same methods, but with the opposite Pokemon.
No, you will need to trade for them or transfer them via Pokemon Bank to get them in Pokemon Omega Ruby and Alpha Sapphire.
No, there are no roms for Pokemon Omega Ruby and Alpha Sapphire currently nor a working 3DS emulator. (They are also incompatible with the Desmume emulator.)
You have to transfer it from your Pokewalker. You get it on Icy Mtn. Road.
A Razor Fang can be found on Mirage Island and Cresent Isle, which a Item Finder is required to find these items.
There is no roller skate item in Alpha Sapphire.
In the Hoenn Pokedex in Pokemon Omega Ruby and Alpha Sapphire, these are the Electric-type Pokemon you can capture in the wild (These exclude ones from the National Dex): Electrike, Plusle, Minun, Magnemite, Voltorb, Electrode, Pikachu, Chinchou, and Lanturn. By using the Dexnav, you can find Joltik and Luxio. On Mirage Island, you can find Zebstrika, and Elekid in Mirage Mountain. The legendary Pokemon Raikou can also be available for capture, which appear as a Mirage Spot between 0 minutes and 20 minutes of an hour. For example, it can appear at 1:15 pm/am, since it is between 0 and 20 minutes.
In Pokemon Omega Ruby, Latios can be found in Southern Island after obtaining the HM Surf and going to Route 123. To find Latias, you will need to get the Eon Ticket to fly to Southern Island to get her. Pokemon Alpha Sapphire has the same methods, but with the opposite Pokemon.
No, Navel Rock cannot be accessed in Pokemon Omega Ruby and Alpha Sapphire. Lugia or Ho-oh appears in Sea Mauville on the Abandoned Ship after getting the Scanner.
You can catch Skitty in Pokemon Omega Ruby and Alpha Sapphire in the barks of trees.
You battle Kyogre for your chance to capture it in Pokemon Alpha Sapphire after you capture the groudon.
Magikarp
Yes, Tm's in Pokemon Omega Ruby and Alpha Sapphire are re-useable
No, you will need to trade for them or transfer them via Pokemon Bank to get them in Pokemon Omega Ruby and Alpha Sapphire.
Houndour can be obtained by trading from Pokemon X or Y. It cannot be caught in the wild in Pokemon Omega Ruby and Alpha Sapphire.
You will need to trade for Weedle or breed Kakuna. Kakuna can be found only in the Safari Zone in Pokemon Alpha Sapphire and Omega Ruby.