I gotta give it to Tekkamen's, high dodge and hit, high damage, and most of them comes with 2 pilots, and they can all team attack. and
blue earth pwns as the 2nd best help unit next to Mike. I was thinking about the gaogaigar series for the ryu units because of their weapon effects, but they are slow and easier to get hit, and their combined mode don't allow you to use 2 sets of seshins.