Oscar Robertson has the most rebounds per game by a point guard in a season, with 12.5 per game in 1961-62.

what was the most rpg by a pg in a season
Interpreted as:
What was the most rpg with a minimum of 57.4 games played per 82 team games by a pg in a season?
1961-62Robertson2020-21Westbrook2018-19Westbrook2016-17Westbrook1962-63Robertson1960-61Robertson2017-18Westbrook1963-64Robertson1981-82Johnson2019-20Doncic2021-22Westbrook1964-65Robertson1986-87Lever2018-19Simmons1989-90Walker1982-83Johnson2006-07Kidd2017-18Simmons2016-17Harden2021-22Doncic2020-21Doncic2019-20Westbrook2021-22Murray1988-89Johnson1961-62West12.511.511.110.710.410.110.19.99.69.49.19.08.98.88.88.68.28.18.18.08.07.97.97.97.9
NAMESEASONTMGPRPGMPGPPGAPGSPGBPGTPGFGMFGAFG%3PM3PA3P%FTMFTAFT%MINPTSREBASTSTLBLKTOVPF+/-
Oscar RobertsonOscar Robertson1961-62CINCIN7912.544.330.811.411.022.947.88.911.080.33,5032,432985899258
Russell WestbrookRussell Westbrook2020-21WASWAS6511.536.422.211.71.40.44.88.419.043.91.34.231.54.26.465.62,3691,4457507638923312190-87
Russell WestbrookRussell Westbrook2018-19OKCOKC7311.136.022.910.71.90.54.58.620.242.81.65.629.04.16.265.62,6291,67580778414233325245+292
Russell WestbrookRussell Westbrook2016-17OKCOKC8110.734.631.610.41.60.45.410.224.042.52.57.234.38.810.484.52,8022,55886484013231438190+251
Oscar RobertsonOscar Robertson1962-63CINCIN8010.444.028.39.510.319.951.87.79.581.03,5212,264835758293
Oscar RobertsonOscar Robertson1960-61CINCIN7110.142.730.59.710.622.547.39.211.282.23,0322,165716690219
Russell WestbrookRussell Westbrook2017-18OKCOKC8010.136.425.410.31.80.34.89.521.144.91.24.129.85.27.173.72,9142,02880482014720381200+383
Oscar RobertsonOscar Robertson1963-64CINCIN799.945.131.411.010.622.048.310.111.985.33,5592,480783868280
Magic JohnsonMagic Johnson1981-82LALLAL789.638.318.69.52.70.43.77.113.353.70.10.420.74.25.676.02,9911,44775174320834286223
Luka DoncicLuka Doncic2019-20DALDAL619.433.628.88.81.00.24.39.520.646.32.88.931.67.09.275.82,0471,7595735386214260153+253
Russell WestbrookRussell Westbrook2021-22LALLAL129.136.319.38.91.40.35.37.618.341.61.24.228.03.04.665.54362321091071736441-36
Oscar RobertsonOscar Robertson1964-65CINCIN759.045.630.411.510.822.448.08.910.683.93,4212,279674861205
Fat LeverFat Lever1986-87DENDEN828.937.218.98.02.50.42.07.816.746.90.31.123.93.03.878.23,0541,55272965420134167219
Ben SimmonsBen Simmons2018-19PHIPHI798.834.216.97.71.40.83.56.812.256.30.00.10.03.35.460.02,7001,33769761011261274209+116
Darrell WalkerDarrell Walker1989-90WASWAS818.835.69.58.01.70.42.13.98.645.40.00.39.51.72.568.72,88377271465213930173220
Magic JohnsonMagic Johnson1982-83LALLAL798.636.816.810.52.20.63.86.511.854.80.00.30.03.84.880.02,9071,32668382917647301200
Jason KiddJason Kidd2006-07NJNNJN808.236.713.09.21.60.32.74.611.440.61.64.534.32.22.977.82,9331,04165573612723213146+87
Ben SimmonsBen Simmons2017-18PHIPHI818.133.715.88.21.70.93.46.712.354.50.00.10.02.44.256.02,7321,27965966114070278211+385
James HardenJames Harden2016-17HOUHOU818.136.429.111.21.50.55.78.318.944.03.29.334.79.210.984.72,9472,35665990712138464215+425
Luka DoncicLuka Doncic2021-22DALDAL118.034.424.57.01.20.64.49.221.243.32.27.628.63.95.570.537826988771374824-96
Luka DoncicLuka Doncic2020-21DALDAL668.034.327.78.61.00.54.39.820.547.92.98.335.05.27.173.02,2621,8305275676436281152+164
Russell WestbrookRussell Westbrook2019-20HOUHOU577.935.927.27.01.60.44.510.622.547.21.03.725.85.16.776.32,0491,5534514019320255200+124
Dejounte MurrayDejounte Murray2021-22SASSAS117.934.318.48.22.20.52.17.717.444.51.44.133.31.52.173.937720287902452325+43
Magic JohnsonMagic Johnson1988-89LALLAL777.937.522.512.81.80.34.17.514.850.90.82.431.46.77.391.12,8861,73060798813822312172
Jerry WestJerry West1961-62LALLAL757.941.230.85.410.723.944.59.512.376.93,0872,310591402173
StatMuse has season-level data for rebounds per game going back to the 1950-51 season.