Help playthrough final members?

[pinksylveon]

hi just needing help deciding my teams final members for a playthrough.ive gotten past the 8th gym but havent mad it to the nuclear plant yet as im altering my team. i currently have

Raptorch
nucleon
syrenitide
baariette
yatagaryu

all these pokes will have there standard competitive moveset.
im was thinking of adding a dramasama, gellin or frosthra to the team but im unsure... what would be best to add for type coverage??? thanks in advance!