I am trying to beat the steel type gym in heart gold. who are the best for my party?

Definitely keep Quilava; the fire moves might win you the badge alone. Obviously, Scizor and Dratini also (all of Scizor's moves are not very effective against Steel-types, but Dratini's Surf is legit). A good combo would be Stantler and Alakazam, but only use either one if you have both with you: use Stantler's Hypnosis, then switch to Alakazam and do Focus Punch, which will be super effective and will probably hit if the enemy is asleep. Good luck.