Have fun cheating!
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="/">
<xsl:apply-templates select="EscolaNatacao"/>
</xsl:template>
<xsl:template match="EscolaNatacao">
<xsl:copy>
<xsl:apply-templates select="Turma"/>
</xsl:copy>
</xsl:template>
<xsl:template match="Turma">
<Classe>
<xsl:apply-templates select="@numero"/>
<xsl:apply-templates select="FaixaEtaria/@nivel"/>
<xsl:apply-templates select="FaixaEtaria"/>
<xsl:apply-templates select="Dias/Dia" />
</Classe>
</xsl:template>
<xsl:template match="@numero">
<xsl:copy/>
</xsl:template>
<xsl:template match="@nivel">
<xsl:copy/>
</xsl:template>
<xsl:template match="FaixaEtaria">
<Idades>
<xsl:apply-templates select="@idadeMinima"/>
<xsl:apply-templates select="@idadeMaxima"/>
</Idades>
</xsl:template>
<xsl:template match="@idadeMinima">
<Minima>
<xsl:value-of select="." />
</Minima>
</xsl:template>
<xsl:template match="@idadeMaxima">
<Maxima>
<xsl:value-of select="." />
</Maxima>
</xsl:template>
<xsl:template match="Dia" >
<Data>
<xsl:attribute name="dia">
<xsl:value-of select="." />
</xsl:attribute>
<xsl:apply-templates select="@hora" />
</Data>
</xsl:template>
<xsl:template match="@hora" >
<xsl:variable name="hora" select="substring(.,1,2)" />
<xsl:variable name="minuto" select="substring(.,4,2)"/>
<xsl:choose>
<xsl:when test="$minuto != '00'" >
<xsl:value-of select="concat($hora, ' horas e ', $minuto, ' minutos')" />
</xsl:when>
<xsl:otherwise>
<xsl:value-of select="concat($hora, ' horas')" />
</xsl:otherwise>
</xsl:choose>
</xsl:template>
</xsl:stylesheet>