Magic Johnson had the most games with 20+ points and 20+ assists, with 13 games.

which player has the most games with 20 point 20 assist ever
Interpreted as:
Which player has the most regular-season games with 20 or more point 20 or more assist ever?
JohnsonStocktonWestbrookJohnsonThomasNashSkilesNixonDoncicPaulJacksonJenningsSessionsRoseVan ExelMarburyStricklandJacksonKiddAbdul-RaufDouglasMooreWilliamsLeavell1397652221111111111111111
NAMEGPPTSASTMPGPPGRPGAPGSPGBPGTPGFGMFGAFG%3PM3PA3P%FTMFTAFT%MINREBSTLBLKTOVPF+/-
Magic JohnsonMagic Johnson1332627541.925.18.521.22.30.34.38.315.055.40.81.843.57.78.590.15451103045625
John StocktonJohn Stockton921220039.723.62.722.23.80.22.99.313.370.00.91.461.54.05.178.3357243422631
Russell WestbrookRussell Westbrook717615039.125.112.721.41.90.43.69.720.746.91.94.938.23.94.979.4274891332522+59
Kevin JohnsonKevin Johnson616412143.527.33.020.22.30.53.59.718.053.70.00.50.08.010.080.0261181432114
Isiah ThomasIsiah Thomas512011040.424.05.822.02.40.44.010.020.050.00.42.218.23.65.072.0202291222014
Steve NashSteve Nash2494245.824.53.521.00.50.55.58.017.047.12.08.025.06.57.092.992711115+18
Scott SkilesScott Skiles2425044.021.06.525.01.00.03.57.514.551.72.03.066.74.04.588.988132075
Norm NixonNorm Nixon2494136.024.55.020.50.50.02.59.016.056.31.02.050.05.56.091.772101055
Luka DoncicLuka Doncic1312039.231.012.020.00.00.01.012.023.052.21.06.016.76.011.054.539120014+6
Chris PaulChris Paul1202029.820.05.020.03.00.00.08.016.050.03.06.050.01.02.050.03053003+21
Reggie JacksonReggie Jackson1232034.423.02.020.01.00.02.010.018.055.62.05.040.01.01.0100.03421022+24
Brandon JenningsBrandon Jennings1242132.824.00.021.00.00.02.010.021.047.61.06.016.73.05.060.03300021+24
Ramon SessionsRamon Sessions1202444.520.08.024.01.01.02.07.012.058.30.00.06.07.085.74481122-13
Jalen RoseJalen Rose1222044.022.04.020.01.00.04.09.019.047.43.05.060.01.02.050.04441042+11
Nick Van ExelNick Van Exel1232043.023.04.020.02.00.03.08.018.044.42.08.025.05.06.083.34342031+17
Stephon MarburyStephon Marbury1262042.026.01.020.01.00.03.09.015.060.01.03.033.37.07.0100.04211034+20
Rod StricklandRod Strickland1212042.021.012.020.02.00.05.07.018.038.90.01.00.07.09.077.842122052+23
Mark JacksonMark Jackson1212240.021.07.022.00.00.02.06.010.060.02.04.050.07.08.087.54070023+13
Jason KiddJason Kidd1202549.020.04.025.04.00.05.06.017.035.33.010.030.05.09.055.64944054
Mahmoud Abdul-RaufMahmoud Abdul-Rauf1302056.030.08.020.01.00.03.012.027.044.42.08.025.04.04.0100.05681034
Sherman DouglasSherman Douglas1272246.027.08.022.03.00.04.013.018.072.20.00.01.02.050.04683044
Johnny MooreJohnny Moore1222041.022.08.020.05.00.03.09.016.056.32.02.0100.02.03.066.74185031
Gus WilliamsGus Williams1232035.023.02.020.05.00.02.010.022.045.50.00.03.04.075.03525020
Allen LeavellAllen Leavell1242241.024.07.022.01.00.05.09.015.060.00.03.00.06.07.085.74171053
StatMuse has game-level data for assists going back to the 1982-83 season.