1-What is there to do after I won the Pokemon league the first time and..

You could complete your Pokedex. Battle at battle tower, visit the sevii isles etc. There's heaps to do.

A walkthrough on this website might help you in getting the Ruby gem.

To enter the game to see Mewtwo, you have to have 100 Pokemon seen in your Pokedex. Then he will let you in. Mewtwo will be at lvl70.

Ditto is rare and can be caught at: Routes 13, 14 & 15, Cerulean Cave Floors 1, 2 & Basement 1, Pok�mon Mansion Basement 1

1. You can catch Mewtwo, explore the Sevii Islands, or just train your pokemon.

2. I think you have to get the National Pokedex. As well. Also beat the Sevvi islands.

3. I think the owner of the spa gives it to you. If not it's a item found on the mountain itself. You have to beat 6 or 7 island then they move. (the Ruby is inside the tunnel they dig)

Ok first what you need to do is after catching 60 go see prof oak he will give you a National Pokedex you need this to get past the Team Rocket guys then you go talk to the guy you met on first islind and he will tell you to get a gem it will be a Ruby go to mount ember then do the team rocket guys then go inside follow the maze.after you get all that stuff go back to that fellow agian and talk to him ull give him the ruby and he'll give you a pass then go to Four Island and go through the cave ull help out first person you battaled in the Pokemon legue and she'll ask you to help here then go to Five Island or it might be Six Island and go to the ruins not the one on water it's on Seven Island then go to the door with brail on it and heres one of those crazy thing you have to do use Cut and there will be a maze and after you get past it some guy will steal it from you he'll tell you he wants and hes going to sell it to make money

Ditto is found at the grassy place were you show you're badges to get into the Pokemon legue.