A fire type is probably the most useful thing for this gym. Numel, Vulpix and Growlithe are all available by now, check out the pokemon location guide for more information.
Someone else who understands just how difficult the new Shelly is huh? Yeah, I had a lot of trouble with her.
Anyway, welcome to the forums, if you run into trouble with the game don't hesitate to hit me up.
I'm assuming that Maractus has been added into an earlier segment of the game because lets be honest, who's going to pick up a Maractus at this point? Lapras though, I've got no idea.
Firstly, please don't dig up old topics. The post above you is literally a warning towards necroposting.
Secondly, we have a topic for that. http://www.pokemonreborn.com/forum/index.php?showtopic=9720&page=1
To team showcase with you!
Also, go for that nice and powerful Meganium. When you pick Chikorita a reborn nuzlocke is easy mode.
In all seriousness Blaziken is your best bet for victory.