Getting all Kanto starters in X and Y?

I have beaten the Elite Four and somebody is selling me a Mega Stone for Venusaur in a shop in Lumiose City. I have chosen Charizard, and I'm wondering if the only way to get Venusaur is through the trading methods of Pokemon games.

Solution 1:

The kanto starters are available through the friend safari, assuming you have friends of the fire, water, or grass types. You'll find them in their middle evolution. i.e, ivysaur.

Solution 2:

Besides the fried safari you can just use the GTS for them or trade with a friend. After all if you battled sycamore(you usually do as part of the story) he's shown you all three. Just find something cool to use as trade bait and go for it!