That is messed up, but something that can't be avoided unless you really want to turn "Mom" into "Foster Mom" who just raises orphans to become Pokemon Trainers. Like some sort of Trainer farm in a little house in Pallet Town.
That's even more messed up though.
Personally, I think Legendaries should be available, but rarer to catch wild than Shinies. They exist, it gives the sense of a good "hunt" to the game (which, if you're looking for legendaries, makes them all the better to get), and you can have News Reports on the TVs stating which area certain ones were last seen. If you get there on time and get lucky enough to catch it, good for you. If you miss it, keep an eye on TVs throughout your journey for updates.
Not many people will have one at first, but it'll be available to everyone.
Oh, and eliminate the possibility of Breeding legendaries. The last thing we need is some money hungry trainer with a Ditto ruining the experience and rarity of a legendary Pokemon.