hey there,
this is my first rate in a little while so bear with me a bit, and i'll try to help you the best i can. :)
the biggest weaknesses that i can spot off of the bat are opposing cb sawk and any team that can put up SR on you (and keep it up). i know that you do carry a spinner, but the fact of the matter is that ghost-types can easily spinblock armaldo (especially frillish, misdreavus, and golurk) and you have three choice users, two of whom take a quarter or more of their HP just by switching in. if you face any player who can prevent armaldo from spinning away SR, your team struggles mightily. opposing cb sawk are a big problem because every time it comes in, you're forced to sack something to try to deal with it, as charizard is cleanly 2HKOed (OHKOed after SR). it outspeeds or ties all of your pokemon bar rotom-f and charizard, who both obviously cannot switch in.
to be blunt, bastiodon and armaldo together really do nothing but stack weaknesses for you against pokemon like opposing ludicolo, sawk, or even something like gorebyss. they don't really cover something especially important that the other doesn't already deal with (though bastiodon does significantly more for you against birds). i'd advise you to
remove either armaldo or bastiodon; if you cut bastiodon you can slip in SR on armaldo over earthquake (which only hits golurk & steels, really). i would prefer that you keep it since some future changes i will mention will favor bastiodon as a whole, but it's completely up to you. this will help you a ton against cb sawk in particular, giving it less opportunities to threaten your team.
i know charizard is fast & powerful, but it honestly doesn't do as much for your team as you'd like, especially when choice-locked. being locked into fire blast opens opportunities for pokemon like regirock to set up stealth rock and then hamper your team as described before, while being locked into a weaker non-stab attack like hp grass means a multitude of set-up opportunities for all sorts of things, like sawsbuck, exeggutor, etc. i'd like you to either look into some form of
roost set that deals with SR better, or consider using a different pokemon in this slot altogether; while 'zard is awesome, a choice-locked version doesn't really fit in well with this team that doesn't have a super-reliable spinner.
i'd like you to change your rotom-f for
rotom-s - you don't really need blizzard for anything important, and rotom-s gives you a fighting resist outside of charizard which your team is really lacking right now, as well as a solid check to sawsbuck. it's virtually the same set as well, just with air slash in lieu of blizzard. as far as the pokemon that you choose to replace either armaldo or bastiodon, the rest of your team is solid enough that you have the freedom to experiment with what you like, imo. my primary suggestion would be
musharna who has good synergy with the rest of the team and deals with a ton of threats quite well (especially giving you an avenue to deal with amoonguss outside of charizard).
small changes: use
roar > stone edge on bastiodon. keep in mind that bastiodon has like 30 base attack and roaring out SR-weak threats (and other things like musharna) will be a greater advantage for you rather than using a move that has limited opportunities to be successful. you will rarely encounter taunt except from a skuntank, who can't even touch bastiodon anyway (and you can switch out to sawk on the taunt, too!). i'd also like to suggest
positive speed natures on both charizard and sawk. this is important for things like sawsbuck who reams you outside of armaldo / rotom-s as well as jolly cb braviary who can devastate your team with good prediction (or bastiodon out of the way).
summary
replace either armaldo or bastiodon with
musharna / whatever
musharna @ leftovers | synchronize
bold nature (+def, -atk) | 240 hp / 252 spa / 16 spe
psychic / signal beam / moonlight / calm mind or heal bell
subroost charizard over your current set
charizard @ leftovers | blaze
timid nature (+spe, -atk) | 4 def / 252 spa / 252 spe
fire blast / air slash / roost / substitute or focus blast
rotom-s instead of rotom-f
rotom-s @ choice scarf | levitate
timid nature (+spe, -atk) | 4 def / 252 spa / 252 spe
volt switch / air slash / thunderbolt / trick
roar > stone edge on bastiodon
timid and
jolly natures on charizard and sawk, respectively
hope i helped a little and gl with your team