We present a common mathematical formulation of the level statistics of a disordered tightbinding lattice, with one or many flat bands in clean limit, in which system specific details enters through a single parameter. The formulation, applicable to both single as well as many particle flat bands, indicates the possibility of two different types of critical statistics: one in weak disorder regime (below a system specific disorder strength) and insensitive of the disorder-strength, another in strong disorder regime and occurs at specific critical disorder strengths. The single parametric dependence however relates the statistics in the two regimes (notwithstanding different scattering conditions therein). This also helps in revealing an underlying universality of the statistics in weakly disordered flat bands, shared by a wide-range of other complex systems irrespective of the origin of their complexity.