There are many, many things to do now that you have defeated Giygas! Paula will ask you to escort her home, but no matter how you answer she'll tag along anyway. You can now visit almost everywhere you have been throughout the game.
if you go to the room in the summers museum where the shattered man is, you will get one more fight. If you win or lose it, you will be sent to the infinite death screen where you can't get out unless you turn off the system. Let's hope you saved after the Giygas battle.
Open the gift boxes Poo brings out to read letters from family and friends. Try giving Tony's letter to Jeff for an amusing conversation. You can now use PSI Teleport to visit any place in the game without having to worry about enemies.
Collect the Overcoming Shyness book from the Tendas and return it to the library for a little reward! You can also buy the house in Onett if you haven't done so already. Go visit Frank Fly, who now works at the Burger Shop. Monotoli now has a job as an elevator man. You can find Pokey's dad at the cafe in Fourside. Many people have amusing things to say, so talk to them!
You can grab any photo locations you've missed, though Ness and Paula will be the only ones in the picture. You can take Paula back to meet your mother. If you head to Twoson she'll leave your party. You can call any numbers you received throughout the course of the game and find out what happened to them. You cannot save, however.
When you feel you are ready to finish the game, talk to your mom. You will now be treated with a nice photo album of pictures taken during the game. Make sure you stick around until the end of the credits!
And with that, the game is over!