I'm looking to get into competitive Pokemon because I just wanna play with mons I like against other people, and I'll be playing on Showdown, since I don't have any of the new games.

I'm pretty bummed out that SS don't have all the mons, so I'm gonna play the NatDex format. Any tips for building my team? I have zero experience, though I do know about EVs, IVs, and all that. Just the strategy stuff is what eludes me.

I'm mainly looking to put Garchomp (Mega or non) and Toxapex. Any idea how I can build a team around them?