These are the most popular Pokemon characters in Japan, as per the poll below:

https://ranking.net/rankings/best-pokemon-characters#7a4115

1. James.

2. Cynthia

3. N

4.Steven Stone

5. Marnie

6. Brock

7. Ash/Satoshi

8. Lillie

9. Serena

10. Gladion

11. Red

12. Dawn

13. May

14. Raihan

15. Jessie/Musahi

16. Elesa

17. Clemont/Citron

18. Gary/Shigeru

19. Goh/Go

20. Alain/Alan

21. Kasumi/ Misty

22. Mallow

23. Korrina

...

35. Gloria/Yuri

...

41. Leon/Dande

..

48. Bonnie/Eureka.