Jellicent hands down, but let's do a nifty comparison.
Bulky special tank that doesnt have alot of good level up moves but can learn Shadow Ball, Dark Pulse, Will-o-Wisp and of course Surf through TM.
Seeing as your team lacks a decent special wall, this would be a solid pick as it synergises very well with Zoroark and Emboar with its typing and Will-o-Wisp.
If you're patient enough, get one with Water Absorb as Cursed Body is pretty useless.
Very fast special sweeper that learns Psychic through level up as Staryu at level 42. Seeing as you already have 2 decent special sweepers, Galvantula and Sigilyph (and Zoroark if you went special or mixed with it), this would be a redundant addition to your team, considering you already have a Psychic type.