It all depends on which starter Pokemon you get:
Charmander= Suicine (water)
Squirtle= Raikou (thunder)
Bulbasaur= Entei (fire)
My suggestion in catching your dog is having a FAST Pokemon first in your party that knows "mean look" If you switch Pokemon it will run away or use Roar. But......... if it does run away you can alway look in your National Pokedex and you can check in on where it is. It's always on the move so you have to make a stratagy on how you catch it. It's number is 286-288 (i think....): Thznks for Reading! (:
The Legendary Dog (also called a Legendary Beast) that you will get in Pokémon FireRed is determined based on your Starter Pokémon so if you selected Charmander as your Starter Pokémon then Suicune will be the beast that will be roaming around the region, if you selected Bulbasaur as your Starter Pokémon then Entei will be the roaming beast and if you selected Squirtle as your Starter Pokémon then Raikou will be the Legendary Beast that will be roaming around.
moltres
(Excluding legendary pokemon) It should be dragonite...
yes but it depends on who and what you are fighting
It's highly recommended to use it on your legendary dog Pokemon whether it's Raikou, Suicune or Entei.
to get it u need to have charizard.to get suicune use max repel and if a Pokemon appears its suicune!
The legendary dog you find the dog that has a type advantage over your starter.
just go to the pet shop and buy all of them.
they roam around in the wild after you have done everything on the islands but they run away
moltres
You would have had to chosen Charizard as your starter Pokemon. Whichever legendary dog appears depends on your starter. You will find your legendary dog randomly in the wild. (you must beat the elite four first)
No
Entei, Raikou and Suicine are often referred to as the Legendary Beasts or Legendary Dog pokemon. They aren't in Diamond, so you'll have to trade or migrate them. You can do this from the following games: FireRed/LeafGreen, HeartGold/SoulSilver and OmegaRuby/AlphaSapphire.
Raikou is a legendary dog Pokemon. It is not in any specific location in Pokemon Fire Red. Instead, you can find it roaming Sinnoh.
the 3 birds
(Excluding legendary pokemon) It should be dragonite...
Moltres is a legendary Fire and Flying Pokemon. Part of the original trio of legendary birds from the first games, it can be encountered in Pokemon FireRed in Mt. Ember.
the fire Pokemon that professor oak give ( charmander ) and also growthlite ( a dog Pokemon ) Forgive me if spell wrong