For the X Team Charizard, Emolga, and Goodra are absolutes
If I picked Greninja I'd go with: Greninja, Charizard (Mega Charizard X), Gogoat, Hawlucha, Emolga, & Goodra)
If I picked Chestnaught I'd go with: Chestnaught, Charizard (MegaZard X), Golduck, Emolga, Goodra, & ???)
I'm trying to think of a good 6th member for the Chestnaught Team and maybe a better water type than Golduck. Can't you get a Protean Greninja in the Friend Safari?