60/70/
125/
65/105/90
Roserade is one of a few bulky Spikes setters with reliable recovery. It has a lot to love as a defensive Pokemon, like useful abilities and a wide pool of support moves, like Leech Seed, Sleep Powder, Toxic Spikes, Stun Spore and Aromatherapy. Grass/Poison can be a decent defensive type too. The main issues with Roserade are that it's extremely passive, and the competition it faces from other Grass-types. Amoonguss has a bit more offensive presence and Regenerator, Chesnaught can acheive similar mixed defenses and Spike up all the same, and Ferrothorn is still good as ever. Hopefully Roserade can distinguish itself with its unique support characteristics.
Lots of people have mentioned Mega Gardevoir, and for good reason. Any Pokemon with base stats that high to reallocate is definitely worth a mention, and this one is no exception. I've seen mention of fast Mega Gardevoir sets, and physical ones too, but I don't think that's all Mega Gardevoir is capable of.
68/
165/65/
85/135/100: Physical Mega Gardevoir seems a bit viable. It trades Psyshock, Focus Blast, and Calm Mind for a stronger Fairy STAB, elemental coverage, and weak priority. The main draw here is that now its best Psychic move is Zen Headbutt, and it lacks a strong coverage move like Focus Blast.
68/85/65/165/
100/
135: Probably the closest to standard Mega Gardevoir, but much faster. 135 is a solid speed tier, but it's still slower than most leads. This definitely looks like it will be the standard set, though.
68/85/
165/
65/135/100: This set faces a lot of competition from other Fairy and Psychic types, but Mega Gardevoir is among the bulkiest. It aims to be a cleric that can support the team with Taunt, Will-O-Wisp, and Body Slam paralysis. Speaking of which, Pixilate Body Slam lets it maintain a decent offensive presence whilst crippling offensive Pokemon. The main flaw here is that Psychic/Fairy isn't a great defensive type, but Mega Gardevoir hopes to make that up with sheer bulk.
68/85/
100/165/135/
65: Self-Trick Room setter. Click Trick Room and begin tearing through offensive teams. This seems like it would be good against fast offensive Pokemon, but Mega Gardevoir's speed isn't all that low so it would still be outsped by some common defensive Pokemon in Trick Room. Not to mention Chansey, which is the fastest Pokemon in Trick Room.
78/130/111/
100/85/
130
Here's another scary Dragon Dancer, now that it has access to a higher speed tier. With the increased average speed in this metagame, that may not be that important of a change, but Charizard is now capable of outspeeding all but the fastest Shuckles after a Dragon Dance. It even has a bulkier spread (78/130/111/
85/
130/100) which is arguably better than the fast one. Dragon/Fire is a solid defensive type, and with its Special Defense buffed, it can set up on passive Water types much easier, or just Will-O-Wisp threats.
95/
80/
135/110/80/100
Salamence is still mostly outclassed by Dragonite offensively, but now it has the ability to swap its Attack and Defense to become as bulky as its Mega Evolution, except with the ability to hold Leftovers, and always have Intimidate. This lets it act as a possible very bulky Defogger who can check Ground, Fire, and Grass types. Dragon/Flying is a pretty decent defensive type in spite of the Stealth Rock and 4x Ice weakness, and Salamence can make good use of it while still maintaining an offensive presence with moves like Dragon Pulse, Fire Blast, and Hydro Pump.