I thank you for your assistance, but I need something that imports all nodes
inside the table and remove all nested <code> tags before replacing all by a
global <code>

ie:
<table bgcolor="blue">
<tr>
 <td>
  <code>
   a
    <code>b</code>
    <p>hello</p>
  </code>
  c
</...>

must return <code>a b<p>hello</p></code>

I think

 <xsl:template match = "table[@bgcolor='blue']">
   <code>
    <xsl:apply-templates/>
   </code>
 </xsl:template>

will not remove <code(s)> inside <table>

and
 <xsl:template match="table[@bgcolor='blue']">
  <code><xsl:value-of select="."/></code>
 </xsl:template>

will remove all nodes (<br>, <font> ...)