Honestly, if you are using a mega sceptile set with sub, run giga drain instead. Sub can easily wear it down, because it has no reliable recovery and it can't run leftovers. Giga drain still hits pretty hard, and you can get back your HP after subbing, with makes beating stuff like mew easier. If you are going to run leaf storm, run the wallbreaker set, because leaf storm hits insanely hard off of mega sceptile's high special attack, and it's a great hit and run attacker.
Also 1 mon I'm really hyped about is mega pidgeot (if you couldn't tell by my avatar), it gets a 110 base power STAB move to toss around (wait did I mention that move has no drawbacks), coupled with high speed and pretty nice coverage with heat wave, and with it's high special attack, nothing except resists will like taking hurricanes. Yeah it also looks really cool too