Well you get bonus points if you get through a rainbow hoop. It's not like SA2(B) where you got 2000 points for killing over 11?12? enemies with homing attack or bounce attack, because there are now "leader enemies", and when you kill them you get points like this:
Killing the leader which causes the destruction of
3 other enemies : 600
4 other enemies : 1100
5 other enemies : 1600
..always +500 for another enemy