You can't, you need to trade from Poke Transfer.
You can only get Kyogre in Soul Silver in 2 ways. 1. Migrate from Sapphire to Pearl/Diamond and then trade to Soul Silver. 2. Get it in Heart gold and trade it over from there. You can sadly not catch Kyogre in Soul Silver.
You cannot catch Rayquaza in Pokemon Black 2.
You would need to trade for them from Pokemon Black or White, for they are not available in Pokemon Black 2.
no
You can only get latias in pokemon black 2 by link trade or poke-transfer, but you can get latios in pokemon black 2.
You cannot catch Keldeo in Pokemon Black 2. You have to have received it from an event or from someone else.
You can't
A trade is required
You cannot catch Meloetta in Pokemon Black 2 and White 2. You have to receive it from an event, but as of right now, it has not yet been announced for North America.
Rufflet cannot be caught in Pokemon Black 2, you must trade from White 2 or White.
You cannot get Kyogre in PTD because Sam (the creator of the game) banned it from trading and said nobody can catch it. Well you can get it but you have to hack and if you get caught Sam will ban you from the game :(
You cannot get it in black 2 or white 2 but you can trade it across