Weaken raikou when you find it it will run away however when you find it again it should still be weak, make it go to sleep by using hypnosis or sleep powder then start throwing all the ultra balls you have and hope you get it.
Yeah it is possible to catch kyogre with out wasting your masterball you wont have to use it until you see latias and latias requires you to use your masterball.
Raikou appears randomly in Johto. I didn't get it but know. If appears he can run off so careful about every turn. Ultra ball will do the work but hardly, if you don't have Masterball.
weaken it and put it to sleep
you can, the catch is fairly easy even without a masterball although I woul use ultra balls if you arent going to use a masterball. I you knock out reshiram without sAVing before hand you can try again after the credits at dragonspiral tower
A fleeing legendary pokemon
No. You should use your masterball on a wandering legend like Raikou, Entei, or Latias.
try using dusk balls
the strongest pokeball is the masterball. the masterball can catch any Pokemon out of the 493. it doesnt matter what kind of Pokemon it is, the masterball can catch any Pokemon.
I think you should use ur masterball on entei raikou or sourcune and maybey mew not mewtwo
Use something like mean look to keep it from running, then catch it like you normally catch a legendary.
No.
get the last gym bage and go to elm's lab and get a masterball then cach him