Here's one way. Not sure you'll like the gymnastics that it requires:
[x,y]=deal(rand(1,40), rand(1,40)); %scattered input data
scatterCustom(x,y)
function scatterCustom(x,y)
%%Create marker prototypes
t=linspace(-pi/2,pi/2,1000)';
t(end+1)=t(1);
p=polyshape([cos(t),sin(t)]/35);
q=rotate(p,180);
f=@(zz,xx,yy) arrayfun(@(u,v) translate(zz,u,v),xx,yy); %translator
%%Plot
plot(f(p,x,y),FaceColor='b');hold on;axis equal
plot(f(q,x,y),FaceColor='none');hold off
end
