Before you leave in the Phase Distorter II you should make sure you've gathered all of the items and equipment that you'll need for the rest of the game.
Once you leave in the Phase Distorter you will not be able to come back.
Take some time to fix items for Jeff, get items from Escargo Express, stock up on Multi Bottle Rockets and Brain Food Lunches from Dalaam.
In the screenshots you can see that throughout the game I've been stockpiling really good items to use from this last leg of the game.
● Ness has a combination of PSI restoration, at least one revive item, the Franklin Badge and all of the Bag of Dragonite.
● Paula has PSI restoration items as well as a few revive items.
● Jeff is loaded up with Multi Bottle Rockets and a few helpful inventions.
● Poo just has a ton of Brain Food Lunches from Dalaam.