I think that Xehanort has planned all along that he really wants to defeat Sora and his friends before he was in the younger days because in KH DDD,Unknown (Young Xehanort) was a time traveler,and i think he wants to defeat some of the people who was connected to him before he was defeated by time traveling or use his incarnation to get X-Blade,Kingdom Hearts and Keyblade War so easily,such as:
Time Travel:
1.use it to defeat Terra at Land of Departure
2.use it to defeat Ventus at LoD
3.use it to defeat Aqua at Lod
4.use it to defeat Sora in the Dream Realm/Mark of Mastery
5.use it to defeat Riku in the DR/MoM
As Master Xehanort:
1.Create Vanitas
2.send Ventus to Eraqus's place to make him stronger in order to make X-Blade
3.to make Terra consume in darkness and take his body as his vessel
4.to make Braig his pawn
5.kill Eraqus to make Terra more consume in darkness
As Terra-Xehanort:
1.Seal Terra's heart and his memories for temporary
2.make Aqua fell into RoD (i know Aqua wants to save Terra,but i think Xehanort has planned for it)
3.use Terra as a many road to choose from
As Xehanort (Apprentice):
1.be as Ansem's Apprentice to study about the hearts
2.get his memories and kill all Ansem's Apprentice to make an Experiments that is to create a Nobody
As Ansem SoD :
1.Visit Destiny islands to make the world fall into darkness and discouraging Sora for not allowed to go to outside world
2.use Riku as his pawn and his vessel and also make him consume in darkness in order to make him use the keyblade
3.live in Riku's heart after his defeat
As Xemnas :
1.make Organization XIII
2.Battle Sora to get all of his Data and use it to create Xion
3.Invite Roxas to join in order to make Kingdom Hearts
4.use Xion to fuse with Roxas in order to make Sora never awakes
I think that Xehanort has planned all along that he really wants to defeat Sora and his friends before he was in the younger days because in KH DDD,Unknown (Young Xehanort) was a time traveler,and i think he wants to defeat some of the people who was connected to him before he was defeated by time traveling or use his incarnation to get X-Blade,Kingdom Hearts and Keyblade War so easily,such as:
Time Travel:
1.use it to defeat Terra at Land of Departure
2.use it to defeat Ventus at LoD
3.use it to defeat Aqua at Lod
4.use it to defeat Sora in the Dream Realm/Mark of Mastery
5.use it to defeat Riku in the DR/MoM
As Master Xehanort:
1.Create Vanitas
2.send Ventus to Eraqus's place to make him stronger in order to make X-Blade
3.to make Terra consume in darkness and take his body as his vessel
4.to make Braig his pawn
5.kill Eraqus to make Terra more consume in darkness
As Terra-Xehanort:
1.Seal Terra's heart and his memories for temporary
2.make Aqua fell into RoD (i know Aqua wants to save Terra,but i think Xehanort has planned for it)
3.use Terra as a many road to choose from
As Xehanort (Apprentice):
1.be as Ansem's Apprentice to study about the hearts
2.get his memories and kill all Ansem's Apprentice to make an Experiments that is to create a Nobody
As Ansem SoD :
1.Visit Destiny islands to make the world fall into darkness and discouraging Sora for not allowed to go to outside world
2.use Riku as his pawn and his vessel and also make him consume in darkness in order to make him use the keyblade
3.live in Riku's heart after his defeat
As Xemnas :
1.make Organization XIII
2.Battle Sora to get all of his Data and use it to create Xion
3.Invite Roxas to join in order to make Kingdom Hearts
4.use Xion to fuse with Roxas in order to make Sora never awakes
That is all i got.thanks for reading my theory!