There's going to be a lot of Grass. With Virizion and Genesect back in the format, grass will be really powerful. Sceptile/Genesect, Vespiquen, and Exeggutor/Vileplume will probably all do well.
Then again, with all the grass, some Fire decks could see play. The ones that come to mind are Magcargo Ancient Trait, Camerupt EX/Camerupt Double Crisis, and Charizard Combustion Blast.
My play is probably Magcargo/Bats because it takes down grass types, is a non-EX, and can deal with other EXs with Bats. But it loses to mega decks that aren't grass weak.
For the megas, I don't know what to think about T-Tar. It gets Darkrai and Dark Patch in Expanded, but is that enough? It dosen't really need Dark Patch since Mega Turbo exists. Rayquaza might see some play because of it's speed that can hold up against the Grass decks, but it dosen't really gain anything from Expanded that I can think of. I like Manectric, but Sceptile is better for energy acceleration since it also heals and with Superior Energy Retrieval in Expanded, Manectric is outclassed.