you have to use faulse swipe and when you see it again use an ultra ball
1st of all it is Raikou and by roaming Johto
you dont
catch it in the wild
You can't.
It's your opinion, but in HeartGold you can catch Ho-oh, Suicune, Raiku, and Entei, and in SoulSilver you can catch Lugia, Zapdos, Moltres, and Articuno. There are also more Pokemon available in HeartGold than SoulSilver. Edit: The person who last answered this question is wrong, you can catch all of the above Pokemon in both games, not in either or. I know this because I have soul silver and I have suicune, raiku, Entei, Ho-oh, Lugia, Zapdos, Moltres, and Articuno; so obviously you must be able to catch them in both.
ia Ho-Oh Lugia Entie Suicone Raiku and the red gyrados
You can't catch Rotom in heartgold.
It's not A Raikou, its Raikou, as you only get one/two chances of battling him/her and it's legendary I would recomend getting it down to barley any life left and asleep. Catch with a fast ball
you cant catch him in heartgold you can only get him in soulsilver
In HeartGold you can catch Kyogre.
You can catch Mewtwo, Suicune, Entei, Raiku, Ho-Oh, and Lugia.
You can only catch Vulpix in SoulSilver, not in HeartGold. You can catch it on route 36 and route 37.