Unlimited isn't an officially endorsed format.
You are mistaken. From the bottom of page 25 of the current Play! Pokémon Rules and Resources document:
Unlimited decks may contain cards from all Pokémon Trading Card Game expansions and promotional cards that have been released in the United States. Players using cards that have been reprinted in a later expansion must play those cards using the wording of the most recent printing. New expansions are allowed in all rating zones the third Friday after they are released in the United States.
You will also find that the official Pokémon TCG's Ban List page includes a second for the Unlimited Format (even though under it just says "No cards are currently banned in the Unlimited format." I believe we are allowed to post the addresses of things from the official Pokémon TCG website, even if we cannot make them an actual hyperlink, so go here for this (and several other) official Pokémon documents:
The Championship Series does not allow Unlimited Format tournaments for the main events, the ones that contribute to qualifying for the World Championship, but they are still permitted for side events.
As such, we don't have technicality rulings on any of the gazillion contradictions it introduces.
Here we get into a situation because there are official rulings, but a group of volunteers maintains the sight that easily collects and compiles them. That group actually includes several members of the official Rules Team utilized by TPCi... actually, they predate TPCi, having worked with the precursor companies and even Wizards of the Coast. I know it won't mean anything for me to quote the posts made by officials on this group's website stating such things, so you'll have to do some searching for it or PM me (assuming I am allowed to share links in PM - the policies on such things here can get very confusing).
Even if you don't believe me on the Pokémon TCG Ruling Compendium, you know rules were made when the older cards weren't so old, right? Pokémon-EX debuted in February of 2012... before there was an Expanded Format (which was designed to take the place of the Unlimited Format in competitive play). The Expanded Format didn't officially become a thing until September of 2014.
As such, it becomes a personal question. Do you want to consider them the same thing, or not? I have always played where ex and EX are interchangeable. After all, the rules regarding them are exactly the same, and while all EXs are basic, that isn't a mechanic as much as a quirk. There are basic 'ex's as well.[/font]
They aren't pronounced the same. Sadly, the source for this is again from members of the Rules Team. Pokémon-ex has you read the two letters together, like the "ex" in "ex-employee". Pokémon-EX is meant to have you read the "EX" as two different letters, so "Pokémon-E-X". Yes, it is confusing but apparently it made enough sense to the powers-that-be in Japan.
You can play how you like with your friends, but I'm telling you there really are rules for this stuff. I'll need to see if I can track down the older rule books... I think they even explained it in there back when Pokémon-EX were brand new.
Edited by Otakutron, Yesterday, 11:54 PM.
If you do not have Private Messages enabled, it really limits you in discussing the Pokémon TCG.