That's the generic missions, but some of the pregenerated enemies like AIGAION could use a bit of a different scale. I beat it after a relatively tight match using 2 Bargol, a Savin and a Corraich where it managed to destroy the Corraich. For my trouble, I was awarded a Trailblazer.
Early on it is very important to use a mecha with a low MV penalty (-2 at most) or you'll get pwned by a Haiho hammer or Wraith heavy missile barrage or vulcan far too frequently. Once you Mecha Piloting is around 8 or 9 heavier mecha are more usable.
I've mentioned elsewhere that the Savin is the only superheavy mecha worth using, but I'll admit that both the Bargol and Green Pixie can hold their own, at a similar price tag.