You could always have a dedicated HM slave or 2 that you can switch out. I don't know what you're talking about when you say that Sweet Scent can lower Attack stats or that Rock Smash can be powerful (40 base power). Also you have 7 Pokemon listed so...
The least terrible Vespiquen moveset would probably be Toxic, Substitute, Attack Order, and Roost/ Heal Order. Pressure goes well with Toxic stalling. Protect is an option over Attack Order for more stalling capability, but you'll be total Taunt-bait. If this is just against a friend now and then, than you're probably fine using Protect over Attack Order unless you think they'll use Taunt. Roost vs Heal Order depends on whether Roost making you just mono-Bug type on the turn you use it is cool with you. It does make Vespiquen less weak to Rock, Electric, and Ice, and the side effects of making you only single resist Fighting and resist Ground instead of being immune to it are pretty much negligible, not to mention Vespiquen is slow anyway, so it probably won't matter because you lose the Flying type after your opponent moves most of the time, so I'd say Roost is the best option. Leftovers is the best item by far, but Sitrus/Lum Berry are okay, too. Maybe Assault Vest or Rocky Helmet? If you don't like/ can't for some reason use this set, other decent moves are Defend Order, Power Gem, Air Slash, U-Turn, Bug Buzz, and Sludge Bomb, maybe Chesto Berry + Rest. Toxic stalling is still the best option.
For Charizard go with Fire Blast, Solar Beam, Earthquake, and Roost. You can use Focus Miss over EQ if you want, but the accuracy is annoying. Personal preference really.
Funnily enough, Chesnaught can also be used as a Toxic staller, only this time with Leech Seed and Spiky Shield for even more residual damage. Use Spiky Shield, Leech Seed, Toxic, and Substitute. If you don't want a second Toxic-staller/subseeder, replace Substitute/Toxic with Hammer Arm and maybe the other move with Wood Hammer. Leftovers is best, Lum Berry can be used to heal annoying status, Rocky Helmet is good for even more damage, Assault Vest would raise its already mediocre Special Defense. I'd say go with Rocky Helmet because Vespiquen could use lefties more. Seed Bomb can be used if you want to trade Woodhammer's power for lack of recoil. Other decent moves include Taunt, Bulk Up, Dragon Claw, Earthquake, Roar, Shadow Claw, Stone Edge, and Poison Jab.
For Lucario use Swords Dance, Close Combat, Extreme Speed, and Stone Edge/Rock Slide( less power, more accuracy). Shadow Claw can be used over SE/RS if Ghosts are more annoying than Flying types. You can also use a Special set with Nasty Plot, Aura Sphere, Vacuum Wave, and Flash Canon/Shadow Ball. FC to hit Fairies or SB for Ghosts/Psychic types. IMO, Shadow Claw has better coverage, but Flash Cannon is STAB. You could run both instead of Vacuum Wave, but Lucario needs priority to make up for its lackluster Speed. I'd say make Charizard your Mega because Charizard is terrible if not Mega and Lucario can operate fine without it. Use Life Orb or Lum Berry. Maybe Expert Belt.
For Lapras, you could try a set with Ice Beam, Thunder Bolt, Surf, and Heal Bell/Perish Song. Heal Bell to heal status for Lapras or another member of your team or Perish Song to force a switch/ KO something you couldn't otherwise take out. Leftovers is, as usual, the best, but Sitrus Berry works, too, and other members could use lefties more. It's also an alright idea to use Rest in the last slot and go with Chesto Berry.
If you can get a Power Herb, give it to Hawlucha and teach it Swords Dance, High Jump Kick, Acrobatics, and Sky Attack. Use Sky Attack once with Power Herb, then use your newly boosted Acrobatics. Otherwise you may want to not use an item at all and replace Sky Attack with something like X-Scissor, Poison Jab, or Stone Edge/Rock Slide. I'd Say SE/RS is your best option as a replacement. Maybe you could use Lum Berry/Life Orb and replace Acrobatics with another one of the previously mentioned moves.
And finally, for Steelix go with Earthquake, Gyro Ball, Stealth Rock, and Dragon Tail. This is your best bet, but you could otherwise go with Crunch, Roar, the elemental fangs, Autotomize(although you'll want to get rid of Gyro Ball), Stone Edge/Rock Slide, Curse, or Payback. Best items in order are Leftovers, Sitrus Berry, Air Balloon, Assault Vest, and Rocky Helmet. Chesto Berry +Rest over Dragon Tail is also decent.
