Yes, but Suicune is the rarest one.
if your party is not full
nothing really unless you still have more Pokemon to catch POKEMON GOTTA CATCH 'EM ALL!(or do you?)
I'm guessing you have the Nintendo: the best game for the Nintendo is Pokemon Platinum because you can catch all the lengendary Pokemon and it has surprises in it. If you have the Gameboy Advance I recommend Pokemon Emerald or Pokemon FireRed. I like Emerald because you can catch Latios and Latias (i think i spelled there names wrong sorry they're psychic and flying type). I like FireRed because you can catch Mewtwo and Mew. Now if you have the first version of Gameboy you soon play Crystal.
yes
The Red Gyarados can be caught in Pokemon Versions, Gold, Silver, and Crystal at the Lake of Rage, the Red Gyarados is level 55-60. but in soul silver and heart gold you still catch her in lake of rage but she is level 30 and you need a Pokemon who knows surf take the grassy way cause team rocket will make you pay a fine of 1000
You can't catch a hymen if you still play Pokemon.
there is less than a 1% chance of getting an Entei and and equal chance of getting Raikou. you just have to roam Jontoh and hope you get lucky. the more you roam the better your chances get, but they still stay very low.
Yes you can rematch greevil at anytime and he will still have his shadow Pokemon if you defeated them.
Unfortunately, you have to catch, trade, or somehow own every Pokemon in the pokedex. If you had it at one time and traded it, it still is in your pokedex.
No because the man who teaches you how to catch Pokemon will not show you how to catch Pokemon no matter how many times you talk to him plus if he does show you how to catch Pokemon and you go to cinnibar island and try to find missingno it still will not show up ever.
sorry but it is impossible to CATCH mew, but you can still ask for it on Wi-Fi club
If you beat Dialga and Dialga faints, you can no longer catch it.