I always use Expression Interactive Designer when I want to see the full default style of a control, but here I have found a equally easy way: just dump it into XML.

Style style = FindResources(typeof(Button)) as Style; //Get button's default Style
if (style != null)
{
XmlWriterSettings settings = new XmlWriterSettings();
settings.Indent = true;
settings.IndentChars = new string(' ', 4);
StringBuilder strbuild = new StringBuilder();
XmlWriter xmlwrite = XmlWriter.Create(strbuild, settings);
XamlWriter.Save(style, xmlwrite);//Use XamlWriter to dump the style
return strbuild.ToString();
}

It uses the findresources method to find a style and then just writes it out. Might come in handy!