I've just had a quick scan through that XEP and I'd say that Pidgin probably only fits under the 'Core Client' category for 'Core Compliance' and 'Web Compliance'... mostly due to the requirement in other compliance sections to implement experimental XEP's (i.e. XEP's that haven't yet been finalised). A very odd XEP is that 0375, though I guess it being experimental unto itself is probably why it's requiring experimental XEP's.
Just my opinion though, others may have something more useful to comment on. :)