import datetime as dt
import pandas as pd
import csv

start_date = dt.datetime(2019, 4,12)
end_date = dt.datetime(2019, 4,21)
daterange = pd.date_range(start_date, end_date)

XLIST = ['401', 'Pabolo Picasso', '402', 'Justin TED', '303', 'Ariana Great']
YLIST = ['201', 'Donald Ted', '202', 'Einastain', '203', 'Hillary Cloud']
ZLIST = ['301', 'Theresa March', '302', 'Jullian Ass Bad', '303', 'Messi Bro']

i = 0
for date in daterange:
    if i % 3 == 0:
        print([str(date)] + XLIST)
    elif i % 3 == 1:
        print([str(date)] + YLIST)
    else:
        print([str(date)] + ZLIST)
    i+=1

['2019-04-12 00:00:00', '401', 'Pabolo Picasso', '402', 'Justin TED', '303', 'Ariana Great']
['2019-04-13 00:00:00', '201', 'Donald Ted', '202', 'Einastain', '203', 'Hillary Cloud']
['2019-04-14 00:00:00', '301', 'Theresa March', '302', 'Jullian Ass Bad', '303', 'Messi Bro']
['2019-04-15 00:00:00', '401', 'Pabolo Picasso', '402', 'Justin TED', '303', 'Ariana Great']
['2019-04-16 00:00:00', '201', 'Donald Ted', '202', 'Einastain', '203', 'Hillary Cloud']
['2019-04-17 00:00:00', '301', 'Theresa March', '302', 'Jullian Ass Bad', '303', 'Messi Bro']
['2019-04-18 00:00:00', '401', 'Pabolo Picasso', '402', 'Justin TED', '303', 'Ariana Great']
['2019-04-19 00:00:00', '201', 'Donald Ted', '202', 'Einastain', '203', 'Hillary Cloud']
['2019-04-20 00:00:00', '301', 'Theresa March', '302', 'Jullian Ass Bad', '303', 'Messi Bro']
['2019-04-21 00:00:00', '401', 'Pabolo Picasso', '402', 'Justin TED', '303', 'Ariana Great']