Help me with my competitive pokemon team?

First of all, replace Sableye. There are much better Dark types in Johto, like Tyranitar, Houndoom, or even Weavile or Spiritomb in Sinnoh. Also, you might want to consider replacing Camerupt with Arcanine, Typhlosion, Infernape, Blaziken, Charizard, or Magmortar. Try to avoid using 2 of the same type. Maybe you would want to replace Poliwrath with something with better offensive capabilities like Milotic, Swampert, Feraligatr, Starmie, or even Vaporeon. Finally, replace Exeggutor, it just has too many weaknesses. Swap it out with an Alakazam, Gardevoir, Gallade, or Metagross.