I can't figure out exactly what your asking, but I'll give you both.
1. Trade Haunter for a Xatu in Pewter City or trade Haunter for a Steelix in Olivine City.
2. Trade Kadabra for a Steelix in Olivine City.
Since Wi-fi is shut down, trading would be much harder than usual. Now, find a friend, and link trade with them. They still allow trading with friends (battles, trades, etc.) From this, you can get a Gengar and Alakazam.
Source: http://www.serebii.net/heartgoldsoulsilver/trade.shtml + Own Knowledge