I've been trying to come up with a fool proof team to take on the Battle Maison/Institute with. So far I have:

Durant @ Focus Sash
Ability: Truant
EVs: 252 HP / 4 SDef / 252 Spd
Jolly Nature
- Entrainment
- X-Scissor
- Thunder Wave
- Baton Pass

Ninjask @ Leftovers
Ability: Speed Boost
EVs: 248 HP / 224 Def / 36 Spd
Impish Nature
- Swords Dance
- Substitute
- Protect
- Baton Pass

The final member will be an all-out attacker. Since the AI still refuse to switch out, the idea is:

>lead with Truant Durant
>use Entrainment
>let Durant die or (if I'm slower) BP to Ninjask
>Ninjask alternates between Protect and Substitute/Swords Dance
>BP +6 Attack, Speed and Substitute to all-out attacker
>Sweep with attacker

So what should I use for my attacker? One of my ideas was Haxorus since it already has excellent Attack and decent Speed, as well as having Mold Breaker to deal with Sturdy-users.

And where can I get Truant Durant in X/Y?