Yeah. This does need a lot of help. Here's a bit for the movesets, but someone else is definately going to go off on you about EV spreads and natures even if you said you aren't currently concerned...
Moves in bold provide better alternatives.
Moves not in bold are pretty much fine.
Torterra:
Frenzy Plant-Bad. Hyper Beam's elemental forms are terrible in competitive battles. They pack a lot of damage, but the turn they take afterwards gives opponents the chance to KO you, switch, or power up their Pokemon with stat-moves. You should replace it with a good Rock move perhaps, as that would beat Flying/Ice/Fire. Or maybe Stealth Rock...
Leaf Storm-Use a different Grass move if you're using grass. Torterra is meant for Attack, not Special Attack.
Synthesis
[New Move]-I'd use Earthquake. It's an awesome ground move, and you may as well take advantage of both of Torterra's types.
Salamence:
Hydro Pump-Its bad accuracy makes it incredibly unreliable. Still, it does hit Rock types that could be a problem... I'm not so sure on this one.
Dragon Claw-Your other moves are Special-Attacks. Perhaps DracoMeteor or Dragon Pulse would be the better choice if this is a special attacker. Hydro Pump is on Specsmence. ._. Enlighten me on why it Isn't good now.
Fly-Okay. Unless you have absolutely NO other option an need a move of a certain type (and Salamence can learn plenty of other Flying moves), NEVER use Fly or Dig. They give the opponent the chance to switch and beat your Pokemon's type. For example, say you used Fly to get a super-effective hit on a fighting-type. Well, they could take their chance and switch to an Ice-Type like Lapras, and then hit you with Ice Beam. If you need a Flying move, use Arial Ace or something else, but not Fly.
Fire Blast-Same problem as Hydro Pump, only now there are better choices for that type. Like Flamethrower. Better Accuracy, more reliable, and generally a decent Fire move. The best Fire move, in my opinion. What? Fly Isn't COMPLTELY useless, it has Its uses. Though, I won't mention them.
Lapras:
Hydro Pump-Replace this. Lapras is a Water Type. It does not need to trade power for Accuracy to get in a good hit. There are plenty of other Water moves out there that work better. Water Pulse. Surf. Waterfall. Et cetera. Read the other Hydro Pump. Some people prefer Power, and do well with that.
Ice Beam
Phychic-Meh. Okay I guess. Someone else will probably disagree with me, but it's fairly good and will save you from Fighting Types. And, BTW, it's spelt "Psychic". Enlighten me some more. It was used in 3rd gen.
Blizzard-Unreliable, bad-accuracy, and low PP. Might hit once or twice out of the five times you can possibly use it, IF Lapras survives that long as just an attacker. You already have Ice Beam. You don't need two damaging moves of the same type. Maybe you can fit Rest or Sing into this slot; Lapras needs Rest if you intend to keep it on the field for a while, and Sing could help you out some. Here here, but it has Its uses. Hint: Weather Condition. DP.
Pidgeot:
Aerial Ace
Tailwind-Not sure on this. You don't exactly need the Speed boost with this team and these movesets... But, maybe you really do for some stratagy you are aware of. I won't stop you there. AA was good back in Third Gen.
Fly-Same thing as for Salamence. Only this time, you don't even need to replace it with a new flying move, because it's already got Arial Ace.
Defog-You don't have any moves with particularly low accuracy, so you don't need to lower anything's evasiveness. Again, it just Isn't completely useless.
^You may have noticed my lack of alternitives. I used to train a Pidgeot, but it wasn't much better (long time ago). I'm not sure I could figure out anything else, as it's movepool isn't too great, but I do know that you don't need Fly and Defog for sure.
Cherrim [willing to replace]:
Magical Leaf
Solar Beam
Leech Seed
Petal Dance Holy Crap! Petal Dance, Solar Beam, AND Magical Leaf?
^Replace this altogether. You already have your Grass Type, and all of its moves need revision, perhaps save for Leech Seed.
Rhyperior [willing to replace]:
Horn Drill-Nonononono. Pokemon is not a game in which you rely on sheer luck. Horn Drill has an incredible possibility of never hitting, and thuse you'd have wasted 5 turns for nothing. In competitive battles, every turn counts, and Rhyperior would be destroyed effortlessly if you were relying on Horn Drill to hit. Besides, what's one Pokemon KOed compared to the many you could get with a better moveset? Substitute is widely used, as for Rhyperior they are powerful. ...
Hammer Arm-Rhyperior doesn't need a Fighting Move. Perhaps Megahorn? I've known it to be a pretty useful move. And I've known Hammer Arm to be a good move in some cases.
Stone Edge
Earthquake
