Pretty decent team, using some of my favourites! A few definately need some adjustments though.
Meganium is looking good but could probably benefit from knowing both sunny day and synthesis - it's a bit of a wall so it should definitely have no trouble in deploying these moves. If you start a battle with sunny day, you'll be able to use solar beam instantly and synthesis will put your health up a great deal more - it'll also power up a couple of your other pokemon's moves in the process.
Dragonite seems pretty much perfect for that species, the only slight thing worth thinking about is that it's nature could be put to better use, but that's not really changeable now - very good dragonite!
Crobat shouldn't be using that many special attacks if you've only EV trained it's attack. It'd be worth rethinking some of it's moves and maybe turn it into a sweeper as its speed truly is a huge asset. Cross poison would be reccomended!
Gengar should NEVER be trained in either Hp or any kind of defence - a Gengar is a sweeper and therefore is supposed to go first and knock the enemy out in one or two moves; it should only be trained in Sp Attk and Speed. Also for Gengar, leftovers is essentially a useless item since the idea with sweepers like Gengar is that they kill things quickly and don't stay in battle for long - it shouldn't have to use leftovers at all and would benefit more from a type boosting item or speed boost item. An electric or grass attack (thunderbolt or energy ball) could be a good addition to Gengar aswell seeing as your type coverage from it's attacks at the moment are pretty one sided.
Togekiss is probably my favourite pokemon to use in game, good choice! All in all you've raised a brilliant togekiss, but it's nature is a huge hindrance! It's nature increases its attack with isn't being used and decreases Sp Def - this is a very bad nature for a togekiss. Also, it's EVs probably could've been better used in Sp Attk and then either split between the two defences or simply just put in health. Water pulse doesn't seem like an overly useful move in contrast to it's over moves - maybe think about replacing it with a stronger special move such as ice beam? Also, Togekiss is able to have two abilities: Serene Grace and Hustle - If your Togekiss has Hustle then once again, this is a huge waste - Serene Grace raises the likelihood of secondary affects (such as air slash flinching, flamethrower burning, water pulse confusing, ice beam freezing) whereas Hustle simply raises the attk stat and reduces accuracy of physical moves.
Ampharos is another one of my favourites, good choice again! For a start, your ampharos has a terrible nature. It reduces speed and increases attack - one of the worst possible natures for an ampharos! It's EVs has been well placed - although possible some defence EVs would've been useful as it's only weakness is ground (a fairly common type as your progress). It has a good move set, very standard for an ampharos, but fire punch is a definite no! An ampharos naturally has a low attack stat, so this move will do very little damage. I'd recommend replacing it with either nasty plot to increase its special attack stat, thunderwave to paralyse or trick room to let it go first and blitz the enemy; however if you'd rather stick to use pain inducing moves I'd suggest hyper beam, simply to make full use of its special attack and health.
Overall a very good team, it's refreshing to see someone that's obviously gone for Pokemon they like rather than going for the commonly used power packs - all the best to you and your Pokemon!
