My dream team would have several different looks as it would depend in who I am facing. So I'll just list all my teams.
Fire Team: Arcanine, Charizard, Typhlosion, Torkoal, Moltres, and Ho-oh. This would be a hard team to beat unless dealing with a team full of rock ground or water types.
Water Team: Gyarados (best physical attack in the game for a water pokemon, plus Hyper Beam is a _____), Lapras, Mantine, Kingdra, Blastoise, and Feraligatr. Again, this team would put Misty's to shame.
Grass Team: Venusaur, Meganium, Bellossom, Vileplume, Victreebell, and Tropius. This team makes Erika's look like crap.
Electric Team: Pikachu or Raichu (really how could you have an electric pokemon in your team and not think first of Pika? He's only the most popular pokemon in the game and the face of Pokemon), Electabuzz (really the best electric pokemon in my opinion for his balance in having good special attack physical attack special defense and defense, added to that he learns reflect which raises his special defense even more making him extremely hard to beat), Zapdos (love the legendary birds), Ampharos (like Electabuzz one of the best electric pokemon in the game and the 2nd best special attack in the game for electric pokemon), Magneton (comes in handy for two reasons: Yes he's weak to fire because of his steel type, but in the real pokemon games ground moves don't affect him because his pokemon power is levitate. 2. He has the best special attack in the game for electric pokemon) and Electrode.
Ground Team: Dunsparce, Donphan, Sandslash, Marowak, Nidoking and Nidoqueen
Rock Team: Onix (can't forget him, he and his evolved form have the best physical defense in the game), Golem, Solrock, Kabutops, Omastar, and Nosepass
Psychic Team: Alakazam, Mew, Mewtwo, Celebi, Lugia, and Hypno
Ice Team: Articuno (best ice pokemon ever), Lapras, Sneasel, Piloswine, Walrein, and Glaceon
Flying Team: Pidgeot (hands down best pure flying pokemon in the game, even after five generations), Fearow, Swellow, Dodrio, Crobat, and Mantine
Fighting Team: Hitmonchan, Hitmonlee, Hitmontop, Machamp, Hariyama, and Blaziken
Dark type: Tyranitar, Sneasel, Umbreon, Houndoom, Mightyena, and Absol
Dragon Type: Dragonite (really dragon pokemon discussions start and end with the Gen I pokemon Dragonite), Kingdra, Flygon, Rayquaza, Latios, and Salamence
Poison Team: Muk, Weezing, Crobat, Vileplume, Arbok, Whirlipede, and Nidoking
Ghost Team: Gengar, Misdreavus, Castform, Dusclops, Spiritomb, and Froslass
Steel Team: Steelix, Magneton, Bronzong, Metagross, Aggron and Scizor
Bug Team: Butterfree, Beedrill, Scyther, Pinsir, Ariados, and Yanmega
All around team: Arcanine (Fire), Venusaur (Grass), Feraligatr (Water), Alakazam (Psychic), Raichu (Electric), and Lapras (Water/Ice) would round out my dream team.