How about vivilon? Ok it's a flying type like talonflame but picture show it learning psychic type moves so it could definitely fill the niche of bug/psychic special sweeper.
Also worth considering is dragalge, yes you have a water starter but dragalge loses that typing on evolution.
And you can't go wrong with Aegislash imo.
Vivillon is Bug/Flying, no matter what moves it learns, Dragalge is confirmed Water/Poison and even if it was Dragon/Poison instead, i would still have a repeat type in my party. Aegislash is cool, but i would already be having a Ghost type in my party unless i chose Gogoat as my grass type, which i will NOT be doing
When was it confirmed water/poison? There have been pics showing it was poison dragon.
The site i use with full pokemon listing and all typings says its Water/Poison