Nope, RNG Pokémon are considered as legit Pokémon by the officials because you still catch them in the game legally or hatch them in the game legally, you're just using the random calculated method in the game in order to receive the precise kind of Pokémon that you want.
That depends on what league you are talking about.
In the Pokemon league.
The Pokemon league is where all the elite 4 are(they have strong Pokemon)
Yes, you can use any Pokemon in the Pokemon league.
the best Pokemon for the Pokemon league is definetly latios
Barclays is the official sponsor for the premier league
Pokemon battle arena is better than Pokemon league.
surf around the pokemon league
The Pokemon League isn't in a city. The Pokemon League is on a place of its own. It is above victory road, and is east of Blackthorn city.
technically, when you beat the Pokemon league, you become the champion. but you cannot really fight as a part of the Pokemon league
No, there is no short cut to the Pokemon league building in Pokemon pearl.
in the Pokemon league. Yes, it is but you have to go through a cave to get to it. Look on your map.