Your question cannot be answered with the information currently available.
"More Famous" is too idiomatic for anyone to provide an adequate answer without poll data from various areas & age groups, perhaps even from different socio economic groups.
Without any data of this sort there is no way to really determine which person is more widely known to the general populace therefore any answer would really be speculation, opinion and/or conjecture from the individual who answered.
Pikachu easily. Iconic figure worldwide for well over 15 years now. Eminem... not so much.
PIKACHU!
pikachu is more famous
in japan pikachu is more famous
Pikachu
Eminem is way more famous
Mario considering he was made before Pokemon and Pikachu. .
Eminem is more famous
Eminem
Pikachu
Pikachu
pikachu
pikachu
pikachu