EXEC DB1.dbo.MySP 
EXEC DB2.dbo.MySP 
EXEC DB3.dbo.MySP 
EXEC DB4.dbo.MySP 
EXEC DB5.dbo.MySP 
EXEC DB6.dbo.MySP 

DECLARE @SQL NVARCHAR(MAX)

SELECT @SQL = 
	REPLACE(
		CAST(
			(
				SELECT 'USE ' + QUOTENAME(name) +';' + CHAR(13) + CHAR(10) +
				'EXECUTE schema.procedure;'+CHAR(13)+CHAR(10)
				FROM sys.databases WHERE name NOT IN ('master','msdb','model','tempdb')
				FOR XML PATH('')
			) AS NVARCHAR(MAX)
		),
		'& # x 0 D ;',CHAR(13) + CHAR(10)
	)
--SELECT @SQL
EXECUTE sp_executesql @SQL