In terms of your levels, Sudowoodo should be trained to at least Level 48 to be on par with Lance's team. Your other members are fine.
Now, counters to his Pokemon:
Gyarados: Use your Raikou. That 4x weakness to Electric will likely mean Gyarados goes down in a single hit to either Thunder or Thunder Fang. Not much of an issue.
Aerodactyl: Raikou is the way to go, with super effective Electric moves. Gyarados's Waterfall is also powerful, but be mindful of super effective Rock Slides and Thunder Fangs coming your way.
Charizard: Here's where your Sudowoodo could come in. While it's probably slower than Charizard, it can do serious damage with its Rock moves, and Charizard can't do too much in return.
Dragonites: If you fancy a slightly risky play, Gyarados' Blizzard will likely end them all easily. However, this is unreliable, as Blizzard has just 70% accuracy. If you use Gyarados, be aware that one of the Dragonite has Thunder. Try Sudowoodo, as Rock-type moves will also deal super effective damage. The rest of your Pokemon seem like they could dish out solid neutral damage as well.
Hope I helped, and good luck!