Well, I'm thinking of my team for Sapphire, and either Cacturne or Tropius is likely to be my Grass type. So, what are the pros and cons of each Pokemon (difficulty of training,etc.)? What are their best moves? Also, what will be the first gym I could use them in? I don't want to have to get my Grass type too late.

(Remember, this is just an in-game team)