1. You can RNG for all 3, I've only got 2 in my thread so far because Articuno is being a dick.
2. You can't release them before the Elite4. You must receive the National Dex to get Oak to move to his house in Eterna.
3. You need to faint the other two, then defeat the Elite 4, and then talk to Oak to release them again, with their new starting frames.
4. If you don't defeat them, then they will continue to roam until you do, so yes they are counted as "roamers".
5. Fainting them is necessary, if you run/let them faint you they will just continue roaming until you catch/defeat them. Obviously, if you catch one you cannot re-release it.
2. You can't release them before the Elite4. You must receive the National Dex to get Oak to move to his house in Eterna.
3. You need to faint the other two, then defeat the Elite 4, and then talk to Oak to release them again, with their new starting frames.
4. If you don't defeat them, then they will continue to roam until you do, so yes they are counted as "roamers".
5. Fainting them is necessary, if you run/let them faint you they will just continue roaming until you catch/defeat them. Obviously, if you catch one you cannot re-release it.