Depends on the Game, if your talking just ORAS, then no, you can't get any, but if you have XY, which is the same gen as ORAS, you can get the Kanto and Kalos HA Starters in the Friend Safari, then trade them over if you want. As for the others, they were all in events that passed a long time ago. For Legendaries, I'm pretty sure it's impossible, as all the non-mirage legends(Weather Trio, and Deoxys) don't have HAs and I'm 99% sure that legends in a Mirage Place(can't remember the name of them)are set legends, and you can't get them with HAs. This is also true for the Regi Trio's HAs.
Source: Questions on this site regarding starter HA info, and looking through the legendary pages of Hoenn Legends, and Experience playing ORAS. Also this. So, with this added info,
So to recap:
I'm 100% sure the only HA starters/legends you can get, in the games you suggested, are the Kanto and Kalos Starters in the XY Friend Safari, and no legendary HAs.