Yes, you do have to save them in order to catch Giratina.
Yes; I once did that with Palkia. My starter Pokemon (Torterra) fainted, so I used Luxray and ended up catching Palkia. Good luckcatching those legendaries! :) I've also used my Palkia to catch other legendaries such as Heatran and Giratina.
you can't because it wasn't created for those GBA games.
Pokemon like Anorith, Lileep, Beldum, those kind.
Umm... uh... well you can catch GIRATINA on lv 47... but Dialga and Palkia are on lv 70 to catch... so uh... maybe... Palkia? or Dialga? Choose one of those and your friend has the other... battle eachother! "Give it a try!"
Not normally. In order to get a Giratina in those games, one would have to obtain it in an event, trade for it, or receiving it via the PokeShifter from an older version.
those Pokemon are shaymin, darkrai, and the best arceas.
You cannot catch Celebi in Pokemon Soulsilver, you have to transfer it from Diamond and Pearl (if you have it in those games).
You can't catch those Pokemon on Pokemon Black. You'll have to either trade for them or transfer them from a DS Series game.
Squritle is not one of the starter Pokemon in those games, but you can catch it after you get the National Pokedex.
Ok, acually, you need 7 badges and do Uxie, Azelf, then Mesprit, cuz Mesprit runs all over sinnoh, so get Mesprit or Cresellia, run in between routes until one of those two Pokemon are on your route not the one across from you, then battle the Pokemon and TRY TO CATCH IT AND IF YOUR ON YOUR LAST POKEMON AND ITS ABOUT TO KO, USE YOUR MASTERBALL (IF you didnt waste it on Palkia, Dialga Giratina, Uxie, or Azelf!!!) DONT WASTE THE MASTERBALL BEFORE U CHASE MESPROT OR CRESELLIA!
you catch cobalion
You put honey on the tree to catch Pokemon in which you can only obtain in the game from those trees.