Gengar used Mean Look on Blastoise!
Gengar switched to Skarmory!
Skarmory used Whirlwind!
Would Blastoise stay in or be forced to switch?
Roar would count, too.
No, it would be forced to switch.
>Also, if the affected Pokémon is Roared at or hit with a Whirlwind, they will still be switched out.
>Also, Dragon Tail and Circle Throw will force the affected Pokémon to switch out
Source: Bulbapedia/ Mean Lok