Karen
Lusamine
DJ Mary
Nessa
Sonia
Cynthia (Pregnant)
All mention above already have seggs with Stephen.
....
Some other Pokemon character girls not yet official (Because of their age):
Green (Confirmed, has future child appeared in the story.)
Marnie
Selena
Rosa
Hilda
Zinnia
Etc...
Possible Harem member in the future chapters:
Lorelei
Caitlin
Malva
Diantha
Aster