Petwer city
Digletts are the only Pokemon in Diglett's cave but they appear so often that when you take your first step into the cave that there is a 7 out of nine chance a Diglett will appear
in diglet cave it will take long but he is there he is at level 29 OR Here's a better way, take a Pokemon level 30 or under to diglett's cave. Use a repel and walk around and you will encounter a dugtrio over level 30
You have to get through Diglett's Cave and that should take you to Pewter City. Go south from there and you'll end up in Viridian Forest and then Viridian City. Finally keep going south and you should be in Palet Town. Look on your map. By the way if there is a Snorlax blocking the entrance to Diglett's Cave then play the Poke Flute on your pokegear. You have to tune in first. Snorlax is at level 50.
You don't. You have to go down to Vermillion City first. From there you take Diglett's Cave to just outside Pewter.
After you defeat the elite four and champion (and complete the regional pokedex) you will be allowed to take a cruise to Kanto. In Kanto, the entrance to Diglett's cave is blocked off by a sleeping Snorlax. Later, after you have gotten the upgrade to your radio in Lavender Town, you can return to this Snorlax. Go to your radio and manually tune it to the upmost point in the circle. You will be tuned into a program called "pokeflute" once you have done this, press A when adjacent and facing the sleeping Snorlax and he will wake up and battle you. After you are done with the battle, Diglett's Cave will be right nearby as an enterance to a cave on one of your sides.
You can't get Regigigas in Pokemon Soulsilver or Heartgold. However, Regigigas is available in Pokemon Diamond, Pearl, and Platinum by obtaining Regice, Regirock, and Registeel. Once you have done that, you can take all three of them to the Snowpoint Temple in Snowpoint City to battle a lv.1 Regigigas.
Take Arceus as the main Pokemon to the Alph Ruins, and an old man will take you to a building in the sky. You will meet Cynthia then deposit all other Pokemon besides arceus and follow her to a cave. There stand on the top middle spot and you will get a lv 1 giratina.
Take your DS or DSi with Soulsilver in the slot, go to a Pokemon center, and take a crap on your DS.
johto and kanto
Well, first off you can not capture Kyogre in Pokemon SoulSilver, only Groudon. The only way you can get Kyogre in Pokemon SoulSilver is by trading. However if you had Pokemon HeartGold you would have to first obtain the Blue Orb from Mr. Pokemon. But to do this you must have: -Obtained the National Dex -Defeated Red on Mt. Silver -Obtained a starter from Professor Oak Next you would need to take the Blue Orb to a cave in Route 47 called The Embedded Tower. You would then have to make your way through the cave to find Kyogre at the end at Lv 50. It is the same process for getting Groudon in Pokemon SoulSilver except instead of the Blue Orb you would get the Red Orb.
get an arceus and take it to ruins alph
beat clair, then surf behind the gym into the cave, climb down the latter, and use whirlpool to get to the den. then take the test from the elder and, POOF, gym badge