Considering your Flying weakness, I'd like to point out that you can breed Ice Beam onto Greninja via Remoraid.
For Darmanitan, notable breeding options are Rock Slide via Camerupt/Drilbur, U-Turn via Mienfoo/Zorua or Flame Charge via Tepig/Ponyta. I'd especially recommend Flame Charge because of the Speed boost.
You might want to catch another Leavanny, in E13, Sewaddle will be learning Sticky Web at level 31 and Sticky Web will be fixed (currently broken). It's not really a good user of Swords Dance. With how many Physical attackers you have, I'd give it Screech instead.
Lucky Chant is really not worth a slot, Aromatherapy is rather situational and Wish is useful competitively, not as much when you have potions. You'd be better of using Petal Dance, Calm Mind and Psychic, the latter 2 can be gotten from Spritzee. The Obsidia Dept Store also has berries to cure the Confusion Petal Dance would induce.
To get Heracross's bread and butter set, you can use a Trapinch to pass Earthquake and Rock Slide onto Heracross. It's a pain to level, so you could also, use a level 39 Geodude to get EQ on Dwebble, get that level 29 for Rock Slide and then you can pass both onto Heracross.
For Tyrunt, I'd seriously recommend Dragon Dance by having it breed with Altaria (found by headbutting trees in Aventurine Forest). There's also 2 accuracy boosting items in the O.Dept Store. One always boosts accuracy by 10%, the other by 20% if you get outsped. That way, Head Smash would have 88%/96% accuracy.
(Regarding breeding, whoever has a move you want to pass on must be male)