let's assume we wanna change terminal type, here is short putty.bat file:

@echo off
set CMD=reg query HKCU\Software\SimonTatham\PuTTY\Sessions

for /f %%i in ('%CMD%') do (
rem echo %%i
reg add %%i /v TerminalType /t REG_SZ /d "xterm-256color"
)
rem "TerminalType"="xterm-256color"