Please find attached a script that will go through all attributes and change every Char data type (without specification if the length is in BYTE or CHAR) to Varchar2.
Example: Char(20 BYTE) will be changed to Varchar2(20).
The script works for all supported Oracle versions.
Please execute the script in Scripting Window (Tools menu, Expert mode has to be on - Settings | Options | General | Expert Mode checkbox).
If you have any questions, please write us back. Thanks.