I am the gate trainer of THIS floor!
I was thinking of doing planned playthroughs of both HeartGold and SoulSilver and was wondering what people thought of my teams. I don't need people saying things like "The main game is so easy you can beat it with anything". Also, for a starter-only run which starter is the best and a one-Pokémon only run which would be the best Pokémon to catch?
Feraligatr is best suited for physical attacking. Waterfall, Ice Punch, Superpower and Crunch would be a good set, unless you're willing to breed for Dragon Dance, in which case use it in place of Crunch.
Ampharos really is pretty awful. It has terrible Speed and a shallow movepool. If you insist on using it, the best you'll get is something like: Thunderbolt/Discharge, Focus Blast, Signal Beam, Light Screen. Really awful in comparison to pretty much any other Electric type you can get except like Pachirisu.
Arcanine is also suited for physical combat with his stat layout. Flare Blitz, Thunder Fang, Crunch and Dig is probably the best you'll get in-game.
Dark Pulse is completely redundant on Gengar. The only thing it hits that Shadow Ball doesn't hit harder is Normal types. Replace this with Focus Blast. Also, Dream Eater is a gimmicky concept. Thunderbolt would serve you much better in this slot.
Dragonite looks good for in-game. I'd personally go Fire Punch > Stone Edge, but it's whatever.
Meganium is honestly one of the worst Pokemon to use in-game (and competitively). It has terrible stats that lean defensively without any instant recovery outside of Rest, and has a shallow offensive movepool. For in-game... jeez... something like Giga Drain, Earthquake, Toxic, Protect while holding Leftovers seems... uhh... okay, I suppose. Honestly, Meganium is just terrible.
Fly/Brave Bird, Return, Roost, U-Turn. Pidgeot is outclassed by Fearow, Dodrio and Skarmory, as they can do what Pidgeot does, just much better than it does it.
I'd go with Nasty Plot instead of Ominous Wind. The ability to double your Sp. Attack in one turn is something amazing. Energy Ball > Dark Pulse if you're willing to breed.
Sludge Bomb > Poison Jab, Ice Beam / Giga Drain > Waterfall.
Get one with Technician ability. Night Slash > Slash, Bullet Punch > Iron Head, Swords Dance > Iron Defense.
The one thing I think Richard missed was Toxic Spikes on your Tentacruel. Hazard moves like that aren't all that useful in game, so I'd use both Ice Beam and Giga Drain on Tentacruel over Toxic Spikes and, as Rich said, over Waterfall too.
Thanks for all the info, I'll update the first status with your improvements? Can you suggest another Pokémon that works well on the HeartGold team instead of Ampharos? Doesn't have to be Electric.