>>46685388I've already got most of those covered (Navel Rock ticket lets me catch Ho-Oh and Lugia, and the10ANNIV distribution cart has the three Johto beasts plus an extra Ho-Oh and Lugia too)
As for the Johto starters, I am tempted to just save my file with my R4 once I complete the hoenn dex, then reload it after I pick one of the starters and trade it over to another game so I can get all three without doing the entire game three times over. If you could get one in each Ruby, Sapphire and Emerald i'd probably just suck it up and do all three but since it's only in Emerald, I can't be bothered transferring everything over just to wipe the file and complete it again another two times.
I'm also self-imposing limits on myself as to when I can give myself these mythicals though, just so I can at least feel like I earned them and offset the feeling of cheating, I'm only giving myself Mew when I complete the Kanto dex, Lugia/Ho-Oh when I complete the Johto dex, Jirachi/Deoxys when I comple the Hoenndex, Suicune/Raikou/Entei when I at least catch the one roaming in my game currently, and Celebi once I complete the whole national dex.