I'd go with www.doperoms.com. They have ROMs for all of the games in the Pokemon franchise, or at least before the DS versions of the games anyway. They might have those too, but I haven't checked for them. They have all of the versions in both English and Japanese, and many of them in Spanish, French, German, Italian, and Portuguese. They also tell you ahead of time which ones have mods enabled, are bad dumps, etc. so that you aren't wasting your time wading through dozens of downloads to find the right game for you.
Hope I helped. Good luck and happy gaming!!!
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