I can critique some of your team, but I'm hardly the best at this. I don't know a lot of the "standard" movesets or anything, and have yet to get really into competitive battling with this generation. (Was big into it in the R/B/Y/G/S/C days) So, I'm like you. I'm only willing to put so much effort into Natures.
Anyway.
Gyarados: Go with Waterfall over Aqua Tail, IMO. More PP, nice special effect, perfect accuracy. Don't know what would be a good fourth move; don't know what all Gyarados can learn, now. My old Ruby Gyarados had Return, and Earthquake. Dragon Dance and Ice Fang are yummy.
Mr. Mime: You don't need really Baton Bass. Both Reflect and Light Screen stay in effect from regular ol' switching. Instead.... hmmm. If you're really keen on the whole barriers theme you could go with Safeguard. I find Safeguard is handy in a lot of situations; more so than Reflect/Light Screen, even. Or try Substitute, to be annoying. Or just some decent, non-Psychic type special attack.
Luxray: On paper, Discharge looks a lot better than Thunder Fang. Thunder Fang only has 65 BP and isn't even 100% accurate. I know Luxray's attack is higher than special attack, but... I'd be tempted to go with Discharge, myself. Just be careful, as Discharge targets all other pokemon in double battles. Scary Face is kinda icky to me, I don't really find I use it much.
Honchkrow: ??? Haven't traded for a Murkrow, yet. But Night Slash seems like a logical choice, given the Ability. Keeping Fly should be okay, but then try to ditch Wing Attack for some... thing... I dunno. Roost is nice, if you find it's got enough defenses to take a few hits.
Some stuff to think about. Perhaps my noobish advice will prompt someone more experienced to go "no, no, that's no good". ^_^;