Thank you all so much for your help. The example data was not correct as you pointed out. The input and desired output should have been as follows:

Input
...
Output
...

In this case there only needs to be either <Individual> or <Business> under <Entity>. Either the registration is for an individual or business. Both should not exist in the same file. Because the business registration information is being pulled from a legacy system certain information required in the XML may not be available, such as <MailingAddressType/> and <MailingAddressLine2/> as in the preceding example. However, if any descendant element of a child has a text value such as <MailingAddressLine1>123 Street</MailingAddressLine1> it's parent and siblings all need to be copied even if those siblings have no text value the nodes need to be copied.

If no descendant elements have a text value as is the case with <Individual> that node and all descendant nodes of that element need to be stripped out. Wow, I hope that wasn't too confusing.

All the templates I have used thus far will strip out any element with no text value, which removes the needed (dare I say required) elements of <MailingAddressType/> and <MailingAddressLine2/> under the <Address> element.

T:\ftemp>type cindy.xsl
<?xml version="1.0" encoding="US-ASCII"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                version="1.0">

<!--preserve all elements whose descendant has text or who has a parent that
    has a leaf child with text-->
<xsl:template match="*[.//*[normalize-space(.)] or
                       ../*[not(*) and normalize-space(.)]]">
  <xsl:copy>
    <xsl:copy-of select="@*"/>
    <xsl:apply-templates/>
  </xsl:copy>
</xsl:template>

<xsl:template match="*">
  <!--do nothing for elements that don't have a text value descendant-->
</xsl:template>

<xsl:template match="@*"><!--identity for all other nodes-->
  <xsl:copy>
    <xsl:apply-templates select="@*|node()"/>
  </xsl:copy>
</xsl:template>

T:\ftemp>type cindy1.out
<?xml version="1.0" encoding="utf-8"?><Registration>
     <UserName>DID1901</UserName>
     <ActivityType>25</ActivityType>
     <ActivityDate>2008-10-30T12:10:26</ActivityDate>
     <RegistrationCounty>19</RegistrationCounty>
     <Registrants>
          <Registrant>
               <Entity>

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