Considering at the very least the Serperior and the Staryu are hacked (since Contrary Snivy hasn't been released and Staryu can't get Regenerator at all ever), I'd say a Water Stone is the least of their worries.
As for the team you should be fine really, though for the last Gym you're gonna want to make sure you give Staryu Blizzard (or hack Ice Beam onto it since hell it's already hacked) as insurance since Vibrava isn't the bulkiest mon around (and Gligar should hold the Eviolite, unless again, you have more than one). Anyway, as for the E4, you should be fine as long as you evenly train your Pokemon. Based on typing alone you're going to have to play each Pokemon individually for every member except Marshall, since Archeops can kind of sweep through Marshall if you get it to a high enough level (though break Sawk's sturdy with something else since Archeops is useless if it takes a hit). For N, you're fine if you give up Vibrava/Flygon for Zekrom or Reshiram. Ghetsis is going to be a pain in the ass though without a Fighting-type or a higher levelled dragon than Flygon/legendary but it's like that for everyone. All in all it's a solid all-around team for in-game, definitely not the worst but you could have some better type coverage within your members (grab a Scrafty if still possible and use it over Gligar because Scrafty can crush like 3/4 members of the e4 if it gets a moxie boost rolling).
