What's up with all you people flaming Hoppip? >D It's not Hoppip's fault if you people can't use it. Jumpluff kicks some serious butt with Leech Seed and Sleep powder >D It might be hard to train, but trainer battles are absolutely no problem for it. I assure you Jumpluff will be very useful against Red (assuming it has the right movesets of course).
As for your question about which of your party members you should level up the most: a balanced way of training is the way to go. It's good not to keep too big level differences between your Pokémon (I usually have a level difference of 0-5 levels). It might feel hard to do so much training, but the route west of Ekruteak is an easy place to train your Pokémon to atleast level 30 (I myself usually train my Pokémon to level 36 there)
Dark Venusaur said:
Don't level up a Margikarp because later on in the game you get to catch a shiny Gyarados at the lake of Rage.
:t003:Dark Venusaur
Yea, a Gyarados with low stats and a horrible movepool -_- Besides, it can be quite fun to beat up Bugsy and/or Whitney with a Gyarados (believe it or not, but I actually did. I trained all my Pokémon to level 20 on the route south from Violet city O.o)
Dark Venusaur said:
Isn't Myster gift is when you trade items with another person thats Pokemon is holding that item:t201-qu:. If thats the case just give all of your Pokemon Water stones. Unless you can't get enough.
:t003:Dark Venusaur
Nope, Mystery gift gives you a random item, it can be anything from a Berry to a pink bed or huge Snorlax doll.
*edit* I misunderstood your question >D
I'd say you should ditch either Gyarados or Poliwag, you don't need two water types. Replacing one of them with an electric type wouldn't be a bad idea in my opinion. Jolteon wouldn't really be a bad choice, but you could always try using Ampharos or Magneton too, because Thunderstones are pretty rare in the G/S/C games.
You might consider Slowbro as your team's water type, it's surprisingly strong and can take strong hits easily.
Victreebell might be a good choice if you don't have the patience to train a Hoppip, even though it's underused it can do some serious damage if used right. Too bad the G/S/C games don't have traits, though =/
What your team lacks, though is a physical sweeper. I know Spearow isn't on the list, but Fearow makes a fairly good physical sweeper (especialy in the G/S/C games, where the E4's Pokémon's stats are ridiculously low), but I'd rather go with a Crobat. Wait... Nidoran(male) isn't on your list? Nidoking would make a great physical or mixed attacker for your team, it learns a bunch of strong physical and special moves and its attacks aren't that bad either >D