No, it is not true. Jirachi is not available on Mt. Coronet in Pokémon Diamond, Pokémon Pearl and Pokémon Platinum.
No, you cannot. This is true of all legendary Pokemon.
you need to get 5stars then talk to the guy who says how many times it launched then u can go in it and catch jirachi even tho i never did it myself i no how to but my friend has jirachi ok I'm pretty sure that that whole "go to the moon" thing isn't true, and you never had to catch the legendary trio for Jirachi, you just needed to get to an event distributing Jirachi.
Yes it is true you can get jirachi after getting the Npokedex
yes
No, but catch 200Pokemon in hoenn pokedex and search everywhere and you will encounter this Steel/ Psychic Pokemon Do the Pokemon need to be different?
No.
its false you need 200 hundred Pokemon in the whole game two unlock jirachi
mount Olympus
The only way to legitimately get is it to have participated in the Pokemon event last summer, trade and hope it's legitimate, or to get the bonus disk from Pokemon coliseum, put the Jirachi from that from your Gamecube to your GBA, and send the Jirachi to Pal Park.
True
yes
There is no Pokemon called Jiroxy, it is a rumor that when you breed Jirachi and Deoxys a Pokemon named Jiroxy will hatch but that's not true. although there is an Action Replay code to get it, but when you go in the battle screen it will appear as Deoxys or Jirachi (50/50 Chance)