Mistralton City is the next city which houses a gym. This city is unique in that it houses an airport which is used in Unova to transport cargo internationally. It is slightly affected by seasons and has patches of snow around during winter.

Airport
Mistralton City is home to the first airport in the Pokémon games and gives you access to Lentimas Town and the Nature Sanctuary via plane

Hidden Power Checker
In the Pokémon Centre in Mistralton City, you will encounter a man who will tell you the type of the move Hidden Power on your Pokémon. This is a vital function if you wish to calculate your IVs

Move Deleter & Relearner (BW Only)
The Move Deleter and Move Relearner are found in the same house in Mistralton City in Black & White. This house is located to the right of the Pokémon Centre. The Move Deleter will remove moves freely, but the Move Relearner charges you one Heart Scale per move.

Gym (Black & White)
The Gym is in the north part of the runway and features you having to navigate a maze by shooting yourself out of cannons to reach the gym leader

Gym (Black 2 & White 2)
The Gym in Black 2 & White 2 has had a redesign and is set in the top of an airport hanger where you walk along various platforms, having to shield from the wind when the wind blows.