Silph.Co(Kanto, postgame)
No you do not need to catch Kyogre. You can get a Hoenn starter from a guy named Steven in Kanto.
In Pokemon Heartgold and Soulsilver you can get a Johto starter from Professor Elm, a Hoenn starter from Steven, and a Kanto starter from Professor Oak
In Pokemon Emerald, when you complete the Hoenn Pokedex, Proffesor Birch gives you a Johto starter. In Pokemon HeartGold and SoulSilver, after defeating Red, Professor Oak will give you a Kanto Starter and Steven will give you a Hoenn Starter.
You can get them by visiting Steven Stone at Silph Co. after you defeated Red.
After you defeat Red, go to Steven Stone in Silph Co. in Saffron City, and he will give you one.
Steven is in Silph.co when you have obtained all 16 gym badges he will give you a Hoenn starter pokemon. they are mudkip, torchic & Treeko
First, go to Professor Oak to obtain your Kanto Starter. Then, go to Silph Co. to obtain your Hoenn Starter from Steven, the Hoenn Champion. Go to Mr. Pokemon's to get the Blue Orb to catch Kyogre.
beat the main character from firered and leafgreen, then obtain a kanto starter from professor oak and a hoenn starter from steven in silph co.
Outside of migration from Hoenn itself, Steven Stone gives out a Hoenn starter in Pokémon HeartGold and SoulSilver. In order to receive it, you have to beat PKMN Trainer Red at Mt. Silver.
You first must defeat Red at Mt. Silver. Then, go to Silph Co in Saffron City. Talk to the Hoenn Leader Steven, and choose the corresponding colored stone that matches the type of Pokemon starter you want.
One of the three Hoenn Starters. Treecko, Torchic, or Mudkip.
Turtwig is a Hoenn region starter Pokemon. Thus, it cannot be found in the wild for capture in HeartGold. However, after defeating Red at Mt. Silver, you have a chance to get a Turtwig. Go to Silph Co., talk to Steven (the Hoenn champion), and choose the green stone to get a Turtwig.