Ya know, it'd be great (imo at least) if they brought back the PWT for future games. But it probably won't happen, except for maybe Gen 5 remakes =(
I don't think I ever really had much of a strategy in the PWT.....not like I really ever have much of a strategy when I battle anyway. And I didn't really have a set team or two when I did it, as far as I remember.
But as for advice, you need to have your Pokemon be trained for competitive battles in order to win the tourneys. Using whatever stuff you used to to beat the main game won't cut it. And when you do the Champions tournament.....make sure to plan for Cynthia's Garchomp. That thing is nasty and will wreck you if you're not prepared.