Bit of a change of subject here, but I'd love to see party Pokemon have more uses outside of battle than just HM's. Say I have a Rapidash or Dodrio. Instead of (or in addition to) the bicycle, how about an option to ride your Pokemon? Can you imagine how awesome that'd be? As well as non-HM moves seeing field use: douse a fire with Water Gun/whatever water move. Don't have anything with Cut in your party? That's all right, just use Flamethrower (and get your assed kicked by Smokey the Bear). Use Vine Whip to rappel a ledge. Just a few ideas.
Have you played pokemon ranger recently? Thats sounds exactly like my bro's description
EDIT: beaten
And for everyone who wants multiple save files, look at the number of blocks XD needs on gamecube (46) compared to any other game (1-10), which means that with all the items and pokemon and subquests, there just wouldn't be room for more than one save file