The best replacement for soulsilver is heartgold.

The best alternatives to soulsilver are rated as following:
★★★★★  heartgold
★  pokemon dimond pearl
★  black and white
  heartgold which is better

Your alternative for soulsilver is not listed? Suggest!
Speaking about soulsilver, one probably shouldn't forget about pokewalker.

Other search terms related to soulsilver and their ratings are:
★★★★★ pokewalker
You have in mind a companion for soulsilver and it is not yet here? Propose!



Google Trends

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soulsilver
heartgold
pokemon dimond pearl