Multi-band light curve of SN 2018ibb from 1800 to 18 500 Å (rest-frame) after correcting for the Galactic extinction. SN 2018ibb was first detected by Gaia. The last non-detections before the first detection by Gaia and ATLAS are shown by the downward-pointing triangles. With a rise time of > 93 rest-frame days, SN 2018ibb is one of the slowest evolving SLSN known. The decline of 1.1 mag (100 days)⁻¹ is similar to the decay time of radioactive ⁵⁶Co. After t_max+575 days, the decline steepened to 1.5 mag (100 days)⁻¹. The light curve shows undulations up to t_max+100 days and a longer-lasting bump at ∼300 rest-frame days. Vertical bars represent the epochs of spectroscopy and imaging polarimetry. The absolute magnitude is computed with M = m − DM(z)+2.5 log(1+z), where DM is the distance modulus and z the redshift.