Help beating lance

I can beat the E4 no problem but when it comes to lance I can only take out the Gyarados and his first Dragonite. Here are my pokemon, also what level should I level them to:

Meganium: lvl38
Headbutt
Razor Leaf
Magical Leaf
Frenzy Plant

Gyarados: lvl39
Waterfall
Surf
Ice Fang
Dark Pulse

Ampharos: lvl39
Thunder punch
Discharge
Headbutt
Iron Tail

Magmar: lvl38
Lava Plume
Fire Punch
Faint Attack
Focus Punch

Mamoswine: lvl35
Take Down
Earthquake
Ancient Power
Ice Fang

Ho-oh: lvl46
Fly
Extrasensory
Sacred Fire
Fire Blast

what haplicity said, definitely try to get ice shard on mamoswine, it can''t out speed most of lance's team because its only level. 35. i suggest leveling it up more. gyarados has an ice move and intimidate so you should be able to live dragonites attacks and kill it if you train it to level 45+.
magmar isn't all that useful against lance neither is ho-oh so level up meganium and ampharos just a little bit, it should help.

In general, replace Gyrados' DarkPulse with Payback, isnt Gyrados' attack so much better than its special attack? Or is DarkPulse an attack-based move also? I wouldn't think so but... Also if you still have an Eevee and are willing to work with it, give it a Water Stone and level it up for a beast Vaporeon, something that is invaluable against Lance. Gyrados covers water, I know, but for the E4 only I would perhaps add a Vaporeon. Otherwise I would say just some goo ol' leveling up should work nicely. I have a Glaceon Im working on that should help me beat the E4, haven't actually battled them yet but my Typhlosion is currently lv.53 Im pretty sure that that's a good sign

You definately need to train some more, as well as get more ice moves. You could also get rock moves as all of his Pokemon are weak to rock.

Definately level up your pokemans, especislly garados, teach it some ice moves by TM or whatever, and that ampharos could be usefull.

And get rid of your magmar and ho-oh, get the vaporeon and if you can another ice type.

I don't think he needs help 2 months after posting the thread.
Try not to bump old threads please.
Welcome to neoseeker btw

I think he's already beaten the Elite Four since this thread was bumped two months.