In the interim, while I write the next chapter, I feel like I should give you a list of ALL of Xavier's Pokémon.
Chandelure
Banette
Roserade
Lucario
Aegislash
Delfox
Greninja
Chestnaught
Charizard
Venusaur
Blastoise
Lapras
Gothetelle
Dedenne
Florges
Medicham
Alakazam
Mismagius
Lickylicky
Vivillon
These are all of his Pokémon. All of these you can achieve in-game, and the new chapter is almost finished, so expect it soon.