I just beat the last gym and feel like my final team member (Grapploct) does not hold up to the other ones
My team is
I would say drakloak or dragapult with timid or jolly nature. After circhester, you can use the rotom bike to cross the lake of outrage. It spawns aroun level 55-60 and has a good moveset.
It all depends on what your preference is. But, in my opinion, you're lacking a dragon type. Why not grab a flapple, or evolve a jangmo-o? Perhaps grab some Pokemon with great IVs from some raid dens, or sprint into tall grass to encounter a random Pokemon and add it to your team for fun? But, as I said before, it all depends on what your preference is.