What if you used a cheat like "Catch Trainer's Pokemon"- they are pokemon caught within the game- created by the game but since a cheat had to be used to get it is it a hack?
Obviously.
No.
If you alter/create a pokemon well within the legal limits can you still trade or are ANY alterations considered hacks?
Legit, Legal, and Hacked are all different terms that describe different states of a pokemon's legitimacy.
Legit: You yourself (or someone you know) caught, bred, or received this pokemon without the use of any external devices, or aids (RNG abuse isn't considered either of the two).
Legal: The pokemon is legal within the limits of the game.
Hacked: The pokemon isn't legal within the limits of the game.
These terms were loosely described and there are exceptions, I'm sure.
Is it okay to do a trade-back with a hack for pokedex purposes?
I do not recommend it, as it's very likely to spread hacks even more.
You should be able to find all your needs for your pokedex in the Trade Corner anyway.
I ask these because when I "create" a pokemon in Pokegen (with everything as legal as possible) that I haven't seen or caught-I don't get the dex data because I didn't catch it or trade it, even if its under my name and ID. So If I do a trade back- not only do I get the other person's pokemon's data but I should get my own too when i get it back (its a theory, haven't tested it yet).
Like I said, hacking pokemon into your game isn't the best way of going about completing your pokedex. If you post a shop or just look around, you're likely to find them. There are a lot people even giving them away, epically if it's just a random pokemon needed for pokedex information.
Besides, wouldn't the GTS be easier?