Rare and Legendary Pokemon Locations
Regies: Go past Pacifid Log and into the currents. You might land on a place where you can dive. There will be braille. Yu know. There are other cheats on this. Regice is located between Dewford and Petalburg. Regirock is in the southern part of the desert past Mauville. And lastly, Registeel is located inbetween Fortree and Lilycove.(closer to Lilycove.) It should be a little past the rainy grass place. Oh yeah, and my brother noticed this but, did you know there is a ruinmaniac by every ruin?(Ruins contain Regies) So look for the ruin maniac. ( Regis start off either level 30 or 40. I think 40 but I'm not sure.
Rayquaza: You must have beaten the Elite Four to catch this Pokemon. Go by Pacifid Log and there should be a gap that wasn't there before.
Go in them and into the Sky Pillar. You need a mach bike. Go fast over the crumpled ground and through the stuff in the cave and at the top you'll reach Rayquaza! It should be level 70.
Groudon/Kyogre: When you get to seafloor cavern and they run away, Groudon/Kyogre flee to the Cave of Origin, which is in Sootopolis. Dive in a certain place and there is an entrance. Go above surface and go left. Follow the path and you'll meet Steven and the gym leader. Enter the cave and walla! Follow the cave and you fine them. They should be level 45 and if you have Ruby you'll get Groudon ( Ground type. on the front.) or if you have Sapphire you'll get Kyogre. ( Water type. On the front.)
Latios/Latias: After beating the Elite Four it'll appear throughout the region. Eventually you'll find it and you can catch it. They are level 40. If you have Ruby you'll find Latios, the boy, who's blue. If you have Sapphire you'll find Latias, the girl, which is red. ( I'd think it would be other way in color. Ruby = red. Sapphire = blue. but it other way.)
Jirachi and Deoxys: You need action replay or gameshark. But there are rumors of other ways.
I am unsure of their levels.
Rare Pokemon
Ralts: You can find these inbetween Oldale and Petalburg. They aren't the rarest but are pretty uncommon. They mostly start off level 4 or 5 and are kind of weak but Gardevoirs, the third form of Ralts, have the best special attack.
Absol: Actually isn't rare. You just would think it is. They are almost all I see in the first grass patch place past Fortree. They are most commonly level 27 and can learn awesome moves like Fire Blast,Blizzard,and Thunder. ( By TM of course.)
Waillord: Yes. The biggest of all pokemon at 47 feet 7 inches tall and the evolved form of Wailmer. You can just evolve Wailmer or go to the waters below Sootopolis and by Evergrande. I caught mine at level 37 but thew levels vary. They are very awesome and you need them to catch Regies.
Relicanth: You can catch thease around level 31 by the entrance to Sootopolis. You also need these to catch Regies. They are a really rare water/rock fish pokemon.
Tropius: These aren't the rarest but you can find them in the mimic circle and can learn 4 HMs. Fly, Flash, Cut, and Rock Smash. They are usually level 26. The level may vary.
Chimecho: These are reeeally rare and can be found at the top of Mt. Pyre. I caught mine at level 25. You might find other leveled ones.
Vulpix: These are also found on Mt. Pyre and are pretty rare.
Rhyhorn: These are rare pokemon that you can find in the safari zone but you need a mach bike to go up a slope to their area. Usually 25-30 or so.
Wobbuffet: Also rare safari zone pokemon. usually level 27 or 29.
Wynaut: Either get the egg in Lavaridge or go to Mirage Island which is full of them.
Illumise: West of Mauville on that path full of trainers. You may find Volebeat but I haven't. Illumises are around level 13. ( How come Volbeats don't evolve into Illumise or Illumise into Volbeat!?)
Electrode: You can just find these by the Master Ball in the Magma/Aqua Base (Depends on version)
or you can find them in New Mauville. I caught mine at 25 but there could be other leveld Electrodes.
Skarmory: Skarmorys can be found before Fallabor in the ashes. They are REALLY rare. Usually it will be a Spinda.
Zangoose: One of the rarest pokemon, the rival of Seviper, Zangoose, can only be found past Fallabor. I manged to catch one I think level 17 or 18.
Lunatone and Solrock: Either of these may either be rare or common to you but not for most people. You can find these at Meteor Falls. I caught my Solrock at level 16 only. I haven't seen a Lunatone there because I don't go there a lot but my brother has. Level is unknown forhe isn't the type that follows the motto, " Gotta Catch Em' All!"
Feebas: You can catch these between the Berry Master's house and Fortree. There is a big place to find them but when you fish, they are rare. Super rods are best. Yes, yes, I know you're thinking " Who'd want to catch a Feebas? They're so ugly!" but they evolve into Milotic, which is pretty powerful.
Staryu: You can find these on the beach of Lilycove. Level is N/A.
Bagon: The first stage of the all-powerful Salamance, you can find these in the deep parts of Meteor Falls. I'm not sure of the level but they are good.
Beldum: After beating the Elite Four, go to Steven's house and there is a note and a poke ball. In the pokeball is a level 5 beldum, which will eventually grow into a Metang then a Metagross.
Huntail/Gorebyss: Once you have dive, go to the Sunken Ship. Use dive in some water and you will appear in a place with six doors. You will find keys to doors and items and go through puzzles. Eventually you'll find a gadget someone was looking for. Go to them and trade it for either a Deep Sea Tooth or a Deep Sea Scale. Catch a Clamperl ( Underwater in grass. Commonly found.) and make it hold the Deep Sea Tooth/Scale and link trade it. Your friend will recieve the Clamperl holding the Deep Sea Tooth/Scale which will evolve into a Huntail or Gorebyss, depending on the item. Deep Sea Tooth is Huntail and Deep Sea Scale is Gorebyss. Then trade back and you've got Huntail or Gorebyss.
Hope you can catch some rare or legendary pokemon!
*Note* Sapphire1994 should get credit for Beldum and Huntail/Gorebyss. I know him and he submitted them first onto Sapphire cheats. All other cheats are submitted by me.