>>58827513>If I were to restart my copy of HeartGold in German or whatever HeartGold does not have language selection. The only way to play it in German is to own a German copy. The language selection only started with generation 6 and onward (so the 3DS and Switch games)
>played through it to route 10/11 so I could start mass catching Dittos since that's the earliest you can catch them in any gameI think you mean route 34/35. Route 10/11 are in Kanto and Dittos don't appear there. Now route 34/35 IS pretty early, however Ditto only has a 5% spawn rate in route 34 and 4% in route 35. Route 47 is much later in the game but they have a 41% spawn rate there.
>then transferred the best ones from that catching spree up to ORAS, exactly how much would I be able to change their IVs?You wouldn't. DexNav and other mechanics that manipulate IVs are all to manipulate the IV of a Pokemon before you capture them. Once a Pokemon is captured (or hatched from an egg), it's IVs can't be changed.
Generation 7 did introduce Hyper Training, which makes a Pokemon's IV effectively 31 for battles - but it retains its original IVs for other purposes, like calculating Hidden Power or breeding.
DexNav, once you've increased your search level, lets you capture Pokemon that have at least 3 max IVs. Which 3 stats it is are random. The only other way to catch 3 max IV dittos in gen6 is through the Friend Safari in XY, but with online dead, that would require you to find someone who has a Ditto in their Friend Safari and meet them in person.
Later generation made it even easier to catch high IV Dittos, if you're willing to postpone it to a later generation (In Pokemon Scarlet and Violet, you can catch guaranteed 5 IVs Dittos through raids)
