well the natures on you Torterra and Salamance do not complement their movesets as they have mostly Physical moves and a Special Attack boosting natures which means rebreeding them and that would be tedious.
Oh, You have not specified if this is competitive or not, please do so we can help you more.
As for your Gengar's moveset it is pretty obvious that Dream eater should be deleted as pokemon do not Spontaneously fall to sleep.I suggest the Smogon Set Shadow Ball,Thunderbolt,Focus Blast,Trick/Explosion. We also need you arcanine set unless you are planning on scrapping it all together.
He posted within the in game section so it must be an in game team.
Anyways I know the first thing I like to do is see what each Pokemon's highest offensive stat is and then teach them physical or special moves depending on their highest stat. I also like to teach my Pokemon at least one move that is the same type as themselves. For example since Mamoswine is an Ice/Ground type I would teach it an ice and ground type move.
Mamoswine is a high attack stat Pokemon so your choice of Earthquake is perfect since it's a high powered physical move and a nice stab. As for an ice move Ice Shard may not be that powerful, but the benefit is that you get to make your move first. If you're looking for something a little more high powered I'd go with Ice Fang over Avalanche even if Ice Fang doesn't have perfect accuracy. Mamoswine doesn't really have a wide variety of different type moves so I'd stick with Rock Slide and maybe teach it a normal move. Perhaps Return would go well with it since it packs a pretty high attack once you max out Mamo's happiness.
Metagross is another high attacker so you'll probably want to go with Zen Headbutt over Psychic. Which is a move it learns at level 62. Bullet Punch is really up to you. Like Ice Shard it's nice because it strikes first, but it's not an extremely powerful move. If you're looking for more power you'd probably want to go with Meteor Mash. If you're really worried about Metagross's speed you can keep Agility, but you could also trade it out for Aerial Ace. It strikes first which gets rid of the need of Agility to an extent and it's an interesting move to try out on Metragross. Hammer Arm seems fine to me unless you're looking for something a little more accurate. I'd suggest Brick Break in that case.
Acranine also has a high attack, but its special attack is only 10 points lower if you want to include some special moves. For a fire attack I'd definitely go with Flare Blitz even if it does have some recoil. I'd also settle with Extremespeed and possibly Dig (seeing as its move pool isn't the widest.) If you see the move tutor in Platinum I'd definitely teach it Iron Head.
Once again we have Torterra who is a high attack Pokemon. I think you should keep Earthquake and teach it Wood Hammer by giving a heart scale to the man who knows all Pokemon moves in Pastoria City. You could see the move tutor in Platinum and have it learn Outrage or Superpower. You could even throw a Strength on it. You may want to keep Crunch since Torterra's move pool isn't too exciting either. I'd really get rid of Iron Tail though. The poor accuracy can be a hindrance.
You seem to go for high attack stat Pokemon because Salamance is one too! :) You really want to drop Dragonbreath and either teach it Dragon Claw or Outrage. Outrage can be taught by a move tutor in Platinum. I can understand why you have Fly on it so I'll leave that alone. Brick Break, Steel Wing, and Shadow Claw are also some different type physical moves that could go good with it. Brick Break and Steel Wind could especially come in handy when facing an ice type.
Gengar is your only high special attacker. Shadow Ball is a great Combo with it. You could also try Dark Pulse, Thunderbolt, Psychic, Sludge Bomb, Focus Blast, and Energy Ball. All are high powered special attacks. Sludge Bomb giving it a good stab, but it's only useful against grass types.
