  We discuss meson-meson scattering at next-to-next-to-leading order in the
chiral expansion for QCD-like theories with general $n$ degenerate flavours for
the cases with a complex, real and pseudo-real representation. I.e. with global
symmetry and breaking pattern $SU(n)_L\times SU(n)_R\to SU(n)_V$, $SU(2n)\to
SO(2n)$ and $SU(2n)\to Sp(2n)$. We obtain fully analytical expressions for all
these cases. We discuss the general structure of the amplitude and the
structure of the possible intermediate channels for all three cases. We derive
the expressions for the lowest partial wave scattering length in each channel
and present some representative numerical results. We also show various
relations between the different cases in the limit of large $n$.
