Contrary Serperior and Sheer Force Gatr in Rain? Anyone think these will be relevant.
Serperior, probably not. Its just too weak initially, and takes a long time to set up. Its also spamming the worst offensive type in the game with Leaf Storm. About the only thing I'd use it for is Glare+Swagger spam and a Role Play Mega Latias partner or something that can be
actually scary with Contrary. Talonflame's just going to shit on it anyway, along with every Flying/Fire/Steel/Poison/Bug/Grass type in VGC. So yeah, offensively, Serperior is kind of a joke. Supportively, it might be worth a damn just to spam Glare, and a Role Play/Skill Swap potential.
'Gatr on the other hand, offers some very serious power and doesn't eat a Mega slot or require any setup really. Speed's a bit awkward but the natural physical bulk, priority, power, usable movepool, and pure Water typing don't leave a whole lot to desire. If I wasn't such a Drought maniac I'd give my favorite starter ever his own team. Its a good physical attacker that's worth considering, though it is quite vulnerable to WoW/Intimidate.
Typhlosion, though, seems iffy. Obviously, Scarf+FF+STAB Eruption hurts - add in Sun and you'd better pray you have Wide Guard and Heatran. On the other hand, most WoW users (Rotom-W, Arcanine, Talonflame) pose quite a threat to Typhlosion, and it does have a rather pitiful movepool beyond Eruption. It's something to consider though, even if it needs quite a bit of support.
Meganium is an awesome healer and cleric, one of the very few things to get Heal Pulse + reliable recovery + Aromatherapy/Heal Bell, and is actually one of the better picks for that role, but Leaf Guard really does absolutely fucking nothing for it, just like every other pokemon to get the ability, so I don't see that becoming relevant. Add in the handicap of pure Grass typing, second only to Ice in terms of sheer weaknesses and minimal benefits, and our poor healy dinosaur is still as derp as ever ._.