You should use mostly grass and flying types they would be most effective
I would recommend Ludicolo for its Rain Dish ability is very useful especially if you are in a double battle with a Kyogre.
There should not be 2 champions but i have not completed the game yet.
i defeated him with swampert,ludicolo,rayqaza,aggron,linoone,camerupt
You should definitely get Pokémon Emerald.
There should be a move deleter in Pokemon Emerald, try to find this person and you should be able to delete your moves.
you really should get emerald cause Pokemon ruby and Sapphire are separate and emerald is those 2 put together so instead of getting ruby and getting groudon just get emerald and you can get groudon and kyroge and newer Pokemon
easy stroomish
you should get absol
if i were you id get a blaziken,ludicolo,salamence,flygon,skarmory,and rayquaza or if u want gyarados,milotic, or wailord i gurantee youll be happy and feel good. wish i could find mine
yes you should start over in Pokemon emerald cause you may forgot all the other rare Pokemon if you completed the game you should restart it or you will just be bored of it
emerald ruby
not for emerald but for Pokemon silver for Gba