find the review too long, jump to the Ratings and Summary.
Since the three Regi-Pokémon are so similar, a lot of the text
will be shared.
When Pokémon-ex has been Knocked Out, your opponent takes 2
(C) Block Signal 
If Regice ex is in play, flip a coin. If heads, the Defending
Pokémon is now Confused.
(MMC) Wide Laser
Does 20 damage to each of your opponent’s Pokémon. (Don’t
apply Weakness and Resistance for Benched Pokémon.)
Registeel ex is a Basic Pokémon-ex. This means we really
want to be as close to 120 HP as we can be since a) that is the
maximum we have seen so far for Basic Pokémon-ex and b) it is
worth two Prizes when it is Knocked Out, so its almost like it
has about half to two-thirds of its actual LP. There is an
exception though, and that is 100 HP because of Desert Ruins,
a Stadium card that places a damage counter between turns on all
Pokémon-ex with a maximum HP of 100 in play. Due to it, 100 HP
acts more like 80 or 90. So Registeel ex’s 90 HP is as
good as or better than 100 HP, and is a solid score, even for a
Basic Pokémon ex.
is a Metal Pokémon, which is great. Weakness sees some play,
Resistance sees little play, and most important of all you can
make use if actual Metal Energy cards to reduce the
amount of damage you take.
is Fire Weak. While not the worst, be aware that Firestarter
decks are still widely played and a very solid deck. It may
no longer be the top deck, but it’s still strong. Also,
Magcargo is now widely played, and can hit you hard if the
person running it was smart enough to include a few Rainbow
Energy, Multi Energy, or Double Rainbow Energy
so that it can use it’s big attack. As stated, not the worst,
but far from the best Weakness. The Resistance is sadly
non-existent. The retreat is neither an advantage nor a
disadvantage. It is two: high enough you don’t want to pay for
it (especially a Pokémon that utilizes Special Energy cards),
but low enough that you can if you must.
Personally, I think the first attack shows some smarter thinking
than on the other two “Regi”. Why? Because it is a
simple support attack that gets stronger with Regice ex
in play, but since it is a supporting attack, if you want to use
this on its own, it isn’t a big loss: just a 50% chance at
second attack is pretty good. The effect of Wide Laser is the
same as the effect of Spinning Tail on Sandstorm Steelix
and the pure Darkness-Type Dark Tyranitar. On those
Pokémon, a Stage 1 pays one more Colorless Energy, and a Stage 2
only pays a difference of a Colorless Energy requirement instead
of a second Metal Energy requirement (which would be like a
second Darkness Energy requirement for said Dark Tyranitar).
That is to say, you get the same effect for the attack costs (DCC)
for Dark Tyranitar that you do for (MMCC) from Steelix
and (MMC) for Registeel ex.
second attack especially lends itself to the second attack, as
Metal Energy cards used to pay for the attack will of
course reduce damage taken by Registeel ex, which will
allow that widespread damage to pile up.
This card actually has a use, although like the rest of the
Regi this week, the older Hidden Legends version works well
already. Unlike the others, the Emerald version of Registeel
ex actually does the job of its predecessor as well, though
in a different manner. For those not following, the Hidden
Legends version has the same stats with a protective Poké-Body
that is basically not worth it and an attack for the same costs
that hits the Defending Pokémon for 50 points of damage with 20
to each Benched Pokémon of the same type as the Defending
Pokémon. Problem is, most decks are not mono-colored, so
the Bench damage isn’t very widespread. So if you want the
Bench damage as much or more than the damage to the Defending
Pokémon, I’d actually go with this one.
2.75/5-Like most big Pokémon we review and unlike the other
Regi, Registeel ex could be reasonably competent in
an Unlimited deck, albeit slow. With Slowking to protect
Energy, perhaps Healing Fields plus Gold Berry or
Focus Band to stay alive longer, that 20 damage a turn
would quickly KO most Pokémon played in this format. The main
problem is that even with 3 Metal Energy cards attached,
several Pokémon in this format can OHKO Registeel ex, and
let us face it, Slowking would be what really makes the
3.5/5-Obviously, this rating is for a specific deck. “Heavy
Metal”, which utilizes both Metagross and Metagross ex
also likes the old Registeel ex since they can power up
something else, drop Registeel ex into play, and begin
doing widespread damage… which this version arguably does
better. Note that it functions as a Cleaner here.
1/5-On it’s own, it’s nearly useless. If you do manage to pull
two Metal Energy, which is in this set, it’s pretty sick
so long as you can send it up before your opponent sets up
anything big… or that is a Fire-type.
is a solid Pokémon that is reasonably well made. It works well
in a very specific deck. That being said, looking at all these
cards, they really should have just been “plain” Pokémon instead
of Pokémon-ex, adjusting costs… well, really, probably only
adjusting the “price” of Wide Laser and Emerald Regirock ex’s
HP down a tad, and even that is uncertain.