As much as I love Gardevoir, there's no way she is ever going to fill Blissey's role of special sponge. Her newly improved typing is a huge bonus, but 68 HP vs 255 HP is just no contest, Gardevoir's low HP holds her back from being able to take repeated special hits. Even with 252/252+ defense, her physical defense is nearly identical to a 4/252+ Blissey. Her Mega does nothing to fix her awful physical defense and base 100 speed leaves her easily revenged, so I personally don't see much use for her Mega-evo (not to mention Pixilate is nearly worthless).
However I've used her a lot in NU this gen and she's a great choice, Gardevoir has tons of utility (including WoW which is huge) and hits very hard. Gardevoir will likely have a solid niche as a Dragon counter with her new typing, and will have a many more opportunities to switch in. Trace still works very well in combination to check specific threats like Heatran, and combines well with a Choice Scarf, which is my favorite set. I'm curious to see how viable she will be... at the very least, I'm incredibly happy to know she will be moving on up out of NU!
Let's be honest, Blissey has really lost it's usage this gen. Sure, Blissey has enormous HP and great special defenses, but let's not forget a few key factors here. The introduction of threats such as Aegislash and Mega Kangaskhan, along with old threats like Calm Mind Keldeo, Banded Terrakion, Guts Conkeldurr and Specially Defensive Jirachi hinder it's progress, as all of the latter listed can take advantage of Blissey's nonexistent physical defenses, and set up all over it (Or in Jirachi's case, paraflinch it to death). Even it's own pre-evolution boasts better bulk with the Eviolite.
But we aren't talking about Blissey's flaws are we? It's Blissey vs Gardevoir. Gardevoir boasts better defensive typing, with key resistances to Fighting and Psychic, and a neutrality to Dark and Bug, with bug being important seeing as how Genesect has been moved down a tier, along with an immunity to Dragon, allowing it to check choiced threats such as Garchomp, Dragonite and Salamence. Whereas Blissey, who remains normal this generation, has no resistances, one immunity (which most Ghost types have coverage for) And a weakness to fighting, a type that harbors one of the best, if not THE best physical attacking move-pools in the game. Also, how the hell is Pixalate useless? Before you make Judgement like that, take a look at Gardevoir's move-pool. She has access to Hyper Voice, a 90 power Normal type attack with no drawbacks that can hit through substitutes. Now imagine turning it into a Fairy-Type move with a 117 base power (And that's not even applying STAB yet), coming off a Mega evolution with a whopping 175 attacking, leaving Reshiram and Kyurem-W jealous. With 135 base Special defenses, Keldeo, Latios, Hydreigon, and Espeon, and a fantasic move-pools filled with support options, While Blissey is forced to rely on Flamethrower to keep itself from being complete setup bait for Scizor and Forretress, Gardevoir easily outclasses Blissey in overall tanking capabilities and versatility. Let's be honest, the only thing Blissey has got over Gardevoir is Wish-passing, but that's about it. Mega Gardevoir has much fewer counters than Blissey, and the threat of being outsped can easily be patched up with a Choice Scarf Set:
Mega Gardevoir (F)
Choice Scarfed
Ability: Pixalate
EVs: 252 SpAtk / 252 Spe / 4 HP
Bold Nature
- Hyper Voice
- Shadow Ball
- Hidden Power Ground
- Energy Ball/Psyshock