It's a hedgehog. They use their spines for defence. Chespin's spines harden into Steel armour giving it large defence and attack. Boom, Grass/Steel type. imo, either this or pure Grass seems most likely. Grass/Dark speculation is just people trying to impose the Dark/Fighting/Psychic triangle on everything.
Well, to be completely fair, there are still a lot of possibilities they can go with. So aside from the notion of going 'pure', these are what I've noted thusfar.
- Spines harden: Grass/Steel, or Grass/Rock.
- Spines not only harden, but also secrete poison when struck: Grass/Poison
- Chestnuts are hidden in the ground, and hedgehog burrow: Grass/Ground
- Move used in trailer looks like Night Slash/Aerial Ace: Grass/Dark, or Grass/Flying?
Boom.. That's six different types based on stuff that we have seen, or can deduce with some form of reasoning.
Now, think back to GenIV: Piplup.. Who honestly guessed that those short and stubby wings would develop into blades made of blue metal? I honestly doubt anybody did..
Point being that this could go a lot of ways.
As for Fennekin, I've heard a couple as well:
- Fennec Foxes live in the desert: Fire/Ground
- Fennec Foxes mixed with Polar Foxes: Fire/Ice
- Fennec Foxes, mixed with Kyuubi-lore: Fire/Psychic
- Fennec Foxes, trolled by GameFreak: Fire/Fighting
And for Froakie:
- White hand 'gloves' turn into boxinggloves: Water/Fighting
- Frogs may be poisonous: Water/Poison
- Frogs can jump high: Water/Flying
- Frogs can be amphibious: Water/Ground
- Looks as if it has a cloud on its back, could evolve into thundercloud: Water/Electric
You mean Grass/Dark. There is literally nothing hinting at that but people mostly say it should be that typing. Chestnut's can be very hard which gives a nod to steel types.
Or Rock-types.. Just saying..
You'd have to throw a ground typing there to on Chespin hey? Squirrels hide there nuts in the ground and this kinda of looks like a squirrel thing and Ches for Chesnut? I could see it being ground among dark or fighting.
This is what I wanted to add to that post as well...