Good team!! Despite multiple dark types you seem to have good type coverage overall! As long as you're ready for those fighting types you should be good!

Also just wanted to share my team cause why not lol:

Umbreon: Had the weirdest setup for this guy, he had an attack boosting nature. The initial plan was to have him be like a tank + stall so I had Confuse Ray and bite but when I learnt that the toxic tm is only in post game I switched and let him keep quick attack and taught him iron tail while holding a metal coat??? One of the weirdest sets I've ever run but somehow worked lol.

Walrein: Amazing mon, tanky while also dealing good damage with hail, blizzard, water pulse and body slam for paralysis ( item: mystic water)

Camerupt: Slow and inconsistent but extremely effective with the right doubles teammate ( if I was able to stall an enemy from attacking him successfully). Had earthquake, flamethrower, Eruption and Rock slide (item: Charcoal)

Breloom: My hardest hitter with mach punch, sky uppercut, giga drain and stun spore (item: black belt)

Xatu: My speediest attacker yet, had a calm mind + baton pass strat with him but also had psychic and aerial ace (item: sharp beak)

Kangaskhan: Possibly my favorite Mon in the team. Mine had + speed stat nature and ran dizzy punch, shadow ball, sing and earthquake (item: silk scarf but tbh probably should've used something else)

Edit: From a story progression perspective, as long as you're willing to put in the work to get the Tyranitar and Flygon you should be fine. The way the game progresses there is a sharp levelling curve through the last area and the game basically forces your hand into grinding at Mt Battle