No, there are no underwater routes in Pokemon HeartGold or SoulSilver. The HM Dive is not available in Pokemon HeartGold or SoulSilver.
yes you can
You'll need to trade for it from Pokemon HeartGold. It is not avilable in the wild in Pokemon SoulSilver.
it call headbutt and there is movetutor in ilex forest that teach it to you
you can´t
A Pokemon from a Diamond, Pearl, Platinum, Heartgold, or Soulsilver event.
walk in tall or very tall grass.
yes you can. but if you have Pokemon soulsilver, the first encounter will be a lugia and vice versa for ho-oh.
there is a mew in Pokemon soulsilver but you need to catch all leadndery Pokemon including event Pokemon
no. the battle at victory road is the last encounter with him.
At Route 45 and Mt. Silver, but they're hard to encounter
You cannot actually go to Hoenn in SoulSilver, but you can catch Pokemon from Hoenn on Wednesdays with Hoenn Music on the radio.
Route 44 (15% encounter rate) and in the Safari Zone (Mountain).
because that's how the tradition of Pokemon games for Nintendo goes. theres red and blue then silver and gold then ruby saphirre diamong and pearl and then comes heartgold and soulsilver. the difference is that in heartgold you get ho oh and in soulsilver you get lugia. and you encounter different Pokemon that's the difference
Yes, you can capture Heracross in Pokemon HeartGold (And in Pokemon SoulSilver). You must go to Azalea Town and heabutt into the trees there, and eventually you will encounter one.
You can encounter a water type pokemon in the wild while fishing (the pokemon encountered depends of the rod used and the area you are fishing in) or while you are surfing on a pokemon. You could encounter a water type pokemon by trading as well.
you cant get it in sinnoh you can only get it in Pokemon emerald version, or if you have kyogre in heart gold trade it to soulsilver and you will encounter a rayquaza i don't know where but it will be at level 50 i think. Or you can trade groudon from soulsilver to heart gold and encounter rayquaza