>>56948227THIS. Anyone who says a DS is better than a 3DS (assuming you can only get one of the two) is either a contrarian or has an obsession with playing games with native resolution. A cfw 3DS can play the first seven generations while a DS can only play Gens 3 to 5. Even without cfw, a 3DS can play all gens except Gen 3, though ORAS exists if you want to play Hoenn.
You can also transfer Pokémon up to Pokémon Home and from there to Switch games using Pokémon Bank and Gen 1 and 2 Pokémon to Gen 7+ via Pokétransporter and Bank.
>>56948235Unless you're autistic about catching your Pokémon again using Palpark and waiting the arbitrary 24 hours after transferring six Pokemon, you really don't need a GBA slot. Just use PKSM to transfer. BTW, I have two 3DSs and several Gen 4 and 5 games, so I could theoretically use Poketransfer lab but I still prefer to use PKSM instead since I'm not autistic about pointless minigames. If you really must catch the Pokémon again, then you can just dump the saved onto your PC and transfer over the Palpark data using PKHeX. I suppose you might miss out on the GBA inserts exclusives you can catch in DPPt, but you can catch those on the GBA games and just transfer them over, so you're not missing much.
>>56948370Unless he has physical GBA cartridges, he really doesn't need one. Just make a virtual console 3DS cia for it using Super Ultimate Injector and you can play it whenever you want.