incredible team oyznehsty!
firstly the inly improvement for metagross might be changing bullet punch with zen headbutt and giving it a wide lens.
wide lens is for sale at the coin prize exchange for 1000 coins.
bliss skarm combo, i heard it was good.
seismic toss is good, but flamthrower is good for coverage. (lucario with aura sphere)
leftovers are perfect.
your only trouble with those two would be a well bred infernape.
lucario
no suggestions can be given at this moment in time, satisfactry strength.
gengar is good but not sure about substitute without healing, mayby energy ball to add more coverage to a sweeper like desine.
heracross=good
sleep talk for dream eaters and megahorn for phychics in general while adding grass and dark.
close combat for an extreme amount of coverage including rock, steel, ice, normal and more not to mention more moves against dark.
stone edge=perfect! its biggest weakness being flying (*4) allows you to (if your fast enough) one shot a bird like it was nothing and cause your opponent to rage quit.
altogether an excellent team.
after moves natures and effort values however, there is still one thing you can do however.
ivs or individual values are an exellent way to keep training the best of the best in terms of stats.
simply get the same natured pokemon with the same speicies and check its iv discription (it comes as a sentence down the bottem that states somthing like 'proud of its power') if they are in the same and desired stat group (dicription in the iv section of game mechanics of this pokebase website) in the end,the lv 50 or 100 pokemon with the same ev traing might have different stats, you can pick your best/fav stated pokemon and make more breeds aganst it.
be aware, however, hidden power is based on ivs, so training might be a little bit harder.
yours truly: loomhigh123555