Not sure why you want to screw up a well formed XML document and create something that will be difficult to maintain, but who am I to judge.
Here is one solution.
="1.0"="utf-8"
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:msxsl="urn:schemas-microsoft-com:xslt" exclude-result-prefixes="msxsl"
>
<xsl:output method="xml" indent="yes"/>
<xsl:template match="Root">
<Root>
<Employee>
<Name>
<xsl:for-each select="Employee">
<xsl:value-of select="Name"/>
<xsl:if test="following-sibling::*">
<xsl:text>,</xsl:text>
</xsl:if>
</xsl:for-each>
</Name>
<Age>
<xsl:for-each select="Employee">
<xsl:value-of select="Age"/>
<xsl:if test="following-sibling::*">
<xsl:text>,</xsl:text>
</xsl:if>
</xsl:for-each>
</Age>
</Employee>
</Root>
</xsl:template>
</xsl:stylesheet>