the Lion King was hand DRAWN except for the 
stampede sequence.

HOWEVER, it was NOT painted on cels.

NONE of the Lion King was on cels.

The Little  Mermaid was the LAST DISNEY 
MOVIE to ever be painted on cels.  The Lion 
King came AFTER the Little Mermaid, so it 
was not done on cels.

Let me say that again, the Lion King was hand 
animated, mostly. (hand animated on paper 
just like the Little Mermaid with pencils and 
paper). however, those hand drawn lions were 
then scanned into the computer and colored 
in the computer. No cels.
This does not mean that the computer did all 
the animation. Lion King was not a 3d or 
computer generated film, so to speak. it was 
just colored with a computer. and the 
wildebeast sequence was ANIMATED on the 
computer (to make  that many wildebeast.)

Hope that helps to clarify a little.