The record for scoring the most runs in a bilateral T20I series among full member teams is held by ViratKohli.
231 ViratKohli v Eng 2021 (5 innings)
ViratKohli was undergoing a lean patch before the beginning of the T20I series against England, if you want to call it that. In the series opener as well, Kohli was dismissed for a duck but bounced back in the very next match, scoring an unbeaten 73 to take India to victory.
In the third match of the series, he again made an unbeaten 77. After getting dismissed for just one in the fourth match of the series, Kohli showed his class in 5th and the last match of the T20I series, smashing an unbeaten 82 and played a major role in India’s victory in the series.
All in all, he finished as the top run scorer in the five match T20I series with 231 runs from five innings at an average of 115.50 and a strike rate of 147.13 with the help of 21 boundaries and 9 sixes. The way he dominated the series can be understood with the fact that the next top scorer was England’s Jos Buttler who scored 172 runs from 5 matches.
224 KL Rahul vs NZ 2020 (5 innings)
KL Rahul took to the role of the opener in T20 International cricket for India like a fish to water. In the five match series on the India tour of New Zealand in 2020, Rahul was in sensational form and struck 56 off just 27 balls at a strike rate of over 200 in the first match to set the tone for the remainder of the series.
He finished the five match rubber as the top run scorer with 224 runs from five matches at an average of 56 and a strike rate of 144.52. Rahul, who was well ahead of the second placed batsman with 178 runs in the batting charts in the T20I series, struck 16 fours and 10 sixes.
223 Colin Munro v WI 2018 (3 innings)
Colin Munro was batting on another level altogether in the 3 match T20I series between West Indies and New Zealand in 2018. The New Zealand opener struck 223 runs from just three matches at an average of 74.33 and strike rate of 197.35.
Munro smashed 24 fours and 15 sixes in the series and was clearly the difference in the three match rubber, with Andre Fletcher being the next best batsman with just 73 runs.