I think it is chennai super kings. 246 in IPL 2010
Unsure of international but in the IPL Brendon Mccullum has top score in any form of T20 palying for Kolkata 158* off 73 balls.
The highest total by a team in T20 international cricket is 278/3 by Afghanistan against Ireland in 2019.
Highest T20I score is 260-6 for Sri Lanka against Kenya in 2007 T20 World Cup in South Africa.
258 by sri lanka in 1st T20 world cup
Aaron Finch 156