This paper is an overview of a diagnostics setup for highly spread e+e- beams, to be installed at the PSI Positron Production (P³ or P-cubed) experiment. To be hosted at the SwissFEL facility (PSI, Switzerland) in 2026, P³ is e+ source demonstrator designed to generate, capture, separate and detect nano-Coulombs of secondary e+ and e- bunches, in spite of their extreme tranverse emittance and energy spread. The experiment will employ an arrangement of broadband pick-ups (BBPs) to detect simultaneously the time structure of secondary e+e- bunches. A spectrometer will follow the BBPs and deflect the e+ and e- onto two unconventional faraday cups that will measure their charge. In addition, the energy spectrum of e+ and e- distribution will be reconstructed through scintillating fibers.