Hmm... let's see...
Terrakion... I'm not entirely sure if Choice Scarf is THAT great. I've faced one in Wifi random matchups and I smashed it quite easily. Choice Band might be a better option, or even Focus Sash. But seeing how your Gengar (I think it's perfect, by the way) already has Focus Sash...
Slowbro... I've never, ever considered in using one before, so I have no comments in the using-perspective. I've faced plenty and one-hit KOed them all with Choice Band Outrage so I can say that my opinion on it isn't all that great.
Ferrothorn... wouldn't Sassy nature (+Sp. Def, -Spd) be better suited than Relaxed? With Curse, its Def is going to get really high. You MIGHT consider in having maximum Sp. Def.
Infernape... personally, I'd use Earthquake over Stone Edge because I absolutely hate Stone Edge's accuracy. You might also want Thunderpunch for Water types, but I'm not entirely sure where it'll fit. Keep Mach Punch as you'll need a Priority Move.
Galvantula... I don't see anything wrong with it. I know you should never underestimate the power of STAB Thunder that doesn't really miss.
I am a glitcher, not a cheater. I do not alter game codes, but use what's given to get what I want.
Glitches: the solution to the AI's infinite hax. The Battle Frontier AIs may cheat with statistically improbable events happening at every opportunity, but I laugh at their Pokemon team with No Guard Sheer Cold. They may never miss Sing and Grasswhistle, but they can't pull out a Ninjask with Spore. They may never miss Thunder and Hurricane, but they can't pull out a Jolteon with Water Spout and Hurricane in the middle of a Drizzle set. In short, the AI can kiss my a-
As I believe in fairness in battle, I will not abuse the power. In any and all player battles, only RNG is used. No glitches without prior consent.