i need a new pokemon for my team?

I would say two great choices are A modest/Timid Gengar or Adamant/Jolly Dragonite.

Both have good speed and attack/special attack stats. You do already have a flying type with Aerodactyl, so your ice weakness would be a bit of an issue.. So I would say go with Gengar. It also has respectible defenses and Hp. I am using one in SoulSilver and he has been a great asset! If you like the idea of Dragonite better, then I would suggest replacing Aerodactyl with Gengar, and get the best of both options. It will pay off in the E4 and in any future battles.

I woud also like to say that replacing Hitmonlee was a great decision. He is a pretty poor team member..

If you feel like training a pokemon then catch a Gastly/Haunter. Once my Haunter was at a high level it became a tank and was one of the main reasons why I beat the elite four. Plus it is always good to have a Ghost-type laying around. But if you want to beat the pokemon league fast then go with a dragon type. They are beast and don't need much training in order to be good.

Dragonite for the long run, garydos for the short run or you can either use any of the 3 legendary birds. I prefer articuno because of ice beam. He kills dragon types easily.

Yeah, A dragon type like Dragonite would complement this team well.

Jigglypuff

I highly recommend a dragon type !