L_peak vs. v_peak plane. SN 2023pel and SN 2011kl are marked by red stars. A sample of 7 GRB-SNe (Saez et al. in prep.; purple dots), 31 SESNe (Taddia et al. 2018, orange triangles), and 4 SNe classified as Ic-BL but not associated with GRBs (Román Aguilar & Bersten 2023; Taddia et al. 2018, green crosses) are included for comparison. The pink region indicates the expected location of SLSNe. The gray area indicates a region of high luminosities (L_peak) and low v_peak where Ni models require M_Ni ≳ 0.85 M_⊙. We also show Ni models with fixed energy but varying M_Ni (dashed lines), and fixed M_Ni but varying E (dot-dashed lines), for an ejecta mass of 3.4 M_⊙.