Of the five dark type lines: houndoom, murkrow, tyranitar, sneasel and umbreon... only umbreon is technically accessible in johto
The new dark type... is practically exclusively post game in it's debut

The new steel type is just barely better.
Skarmory is not in gold at all and only after gym 8 with zero trainer rep in the entire game. It's distribution is so poor, most players mistake it for being a Gen 3 Pokemon.
Steelix and Scizor are trade evos blocked until Kanto unless you knew to use thief on Magnemites.
Forretress is not steel until evolution and hidden behind headbutting trees exclusively.
Magnemite is the only feasible steel type to get in a playthrough, and it's a rehash from Kanto with the new type.

The only 2 new fighting types are Heracross, which is behind Headbutt trees, and Hitmontop, only available after the 8th gym with a convoluted evolution method

Fire types are also pretty bad. The 2 new lines, Houndour and Slumga, are both postgame exclusive. The Fire stone which can be used to evolved Growlithe/Vulpix/Eevee is locked to the postgame. Ponyta is only available after the 8th gym.