IV/Nature sets?
Suicune: I think it's set when you pick your starter (well, that's almost when you start the game, but meh).
Mesprit: I think it's when you talk to it.
With regards to Roar, the faster Pokemon goes first and makes the slower Roar user leave the battlefield without letting the slower Pokemon use their Roar. (Exception in GSC, the slowest Roar works and the faster Roar doesn't.)
Suicune: I think it's set when you pick your starter (well, that's almost when you start the game, but meh).
Mesprit: I think it's when you talk to it.
With regards to Roar, the faster Pokemon goes first and makes the slower Roar user leave the battlefield without letting the slower Pokemon use their Roar. (Exception in GSC, the slowest Roar works and the faster Roar doesn't.)



