Honchrow is an amazing poké for reborn, Moxie + sucker punch for the win
Galvantula is just fantastic at the next 3 gyms, so is mawile. Although mawile get sort of destroyed when the fight, fire and ground gyms are sort of in a row. Galvantula does exceed even when type doesn't favors it cause high speed+sticky web is just amazing.
Bewear can help in some gyms, but will struggle against others (aka fire and psychic)
Ludicolo is amazing. I think he only does poorly against the flying gym.
Medicham and lilligant can 1v6 some gyms.
Bronzong can be really useful to set up trick room even agaist fire or ground types, cause you can change his ability to adapt to those.
A Ninetales is OP as hell, just respect the Steel gym and you should be ok.
Walrein is a god with X item abuse, it can destroy every fucking gym with these things and some healing items.
Arcanine is also a great option, but remember to look at Growlithe learnset before evolving it, since it gets some good moves at middle 40's.
I won't talk about all of them rn, but you can ask me if you wanna know some specific ones.