I'm guessing you figured this out by now, but just in case...
Mega Evolutions in the TCG are treated as their own Stage of Evolution that Evolve from the Basic Pokémon-EX form of the relevant Pokémon e.g.
M Manectric-EX Mega Evolves from
Manectric-EX. Mega Evolution does have an additional, special rule and it made the first few sets Mega Evolutions pretty poor; when you Evolve one of your in play Pokémon into a Mega Evolution
your turn ends. That meant no attacking, and you couldn't even Evolve into multiple Mega Evolutions in the same turn.
A workaround for this has been released for most (but not all) Mega Evolutions. Most Pokémon-EX capable of Mega Evolving have a Pokémon Tool that follows a naming scheme: [insert Pokémon]
Spirit Link. For example, if you attach
Manectric Spirit Link to
Manectric-EX and then Evolve into
M Manectric-EX... nothing happens. Which is a
good thing, because that means your turn proceeds as normal instead of ending.
If you attach the
wrong Spirit Link card, then the Mega Evolution rule applies as usual; a
Manectric-EX with
Mewtwo Spirit Link attached can still Mega Evolve into
M Manectric-EX, but your turn ends as if you didn't have a
Spirit Link attached at all. There are some pieces of Mega Evolution specific support, some Mega Evolution specific counters, and some cards that specifically exclude Mega Evolutions from their beneficial effects. In my experience, they are somewhere between the difficulty of running a Stage 1 versus a Stage 2.
BREAK Evolutions are a bonus Stage of Evolution beyond what is normally allowed. No, you don't have to capitalize all the letters for most people to know what you mean, but yes, that is how the Stage is officially written on the cards in both names and effects. When a Pokémon BREAK Evolves, the BREAK Evolution card is placed horizontally on top of the appropriate lower Stage e.g. when a
Zoroark Evolves into
Zoroark BREAK, you make kind of a "t" shape when you place
Zoroark BREAK on top of
Zoroark. This is done because BREAK Evolutions use the Weakness, Resistance, Retreat Cost, Ability (if present), and attacks (if present) of the Pokémon from which they Evolved. Because of this (and/or the wording), you
cannot put a BREAK Evolution into play without the Stage immediately preceding it.
Greninja BREAK must Evolve from a
Greninja, though that
Greninja could have
- Evolved normally from a Frogadier that normally Evolved from a Froakie.
- Evolved directly from a Froakie via Rare Candy.
- Evolved from a Frogadier that was put into play directly by another card effect.
- Have been put into play directly by a card effect like Archie's Ace in the Hole.
Whatever Stage the Pokémon was before it Evolved into a BREAK Evolution, its Stage is now "BREAK"; an effect that works for Stage 2 Pokémon does
nothing for the BREAK Evolutions of Stage 2 Pokémon, Stage 1 Pokémon, or Basic Pokémon. There are no beneficial effects that work only for BREAK Evolutions and two anti-BREAK card effects; one doesn't really matter, but
Giratina (
XY: Black Star Promos XY184) has an Ability that turns off the Abilities of any and all BREAK Evolutions,
including any Abilities the BREAK Evolution has due to its previous Stage.
A BREAK Evolution is on par with the equivalent Stage of Evolution; the loss of Stage-specific support seems to trade evenly with Evolving from something that is usually stronger than what said Stage typically Evolves from. Meaning most Evolving Basic and Stage 1 Pokémon are just stepping stones to reach their highest Stage of Evolution, while the
normally non-Evolving Basic and Stage 1 Pokémon are designed to stand on their own but now don't have to.