Now? Dude, Ho-oh and Lugia haven't had their HA since Dream Radar. (outside of transferring via VC GSC, though Lugia is getting Multiscale as part of the movie tie-in... whether or not anyone outside of Japan sees that in their region is another matter entirely)
Granted, the whole point of the Year of the Legendary Pokemon distributions is to give players the wormhole legendary Pokemon not found in their game. (plus Shiny Zygarde) Most have a third part of their trio locked away unless you bring along the other two, and this event will allow players to do just that. Since none of the Pokemon found through the Ultra Warp Ride have their HA, these legendary Pokemon don't either, nor do they have event exclusive moves. (because of course they don't...)
... uh, you can get them via VC GSC, though I don't know if VC Pokemon are VGC legal. (not that it matters for Ho-oh and Lugia, being usually barred and all) And there's that movie tie-in Lugia that's confirmed to have Multiscale and Hurricane, which it can't normally learn. (even though Aeroblast is nearly as good for the same STAB, and far more accurate without rain support)