So I am relatively new to teambuilding in gen 7. What are some of the more common threats and what would be good against them?
SUMO OU threat chart put together by Jamvad: https://docs.google.com/spreadsheets/d/1NylWu846pwqcHXh4BGqPAjKv0Ef9dYq_U3-BRNYebDg/edit#gid=1747608989
Showdown usage stats for November: http://www.smogon.com/stats/2016-11/
These should be helpful. Of course, the best thing to do is just jump in and get an idea of the meta from experience, even if you lose a lot.
Well some good threats include: -Wishiwashi -The tapus (They are not banned) - The Ultra beasts (they are not banned. Best are guzzlord and celestella)
I recommend this website for team planning!
https://richi3f.github.io/pokemon-team-planner/
Try going with a Pokemon for each stat, like: Gyrados covers Special Defense and Attack. Arcanine covers Special Attack. Snorlax for Defense. etc. I sometimes do this to create good, high stat teams that can really be of help.