It’s possible, but it’s honestly very tedious.
There are two ways Rare Candies can be grinded in these games:
- Pickup at any level. Just shove a bunch of Meowth into your party and go into a bunch of battles and pray you get Rare Candies.
B. There’s an NPC in the post game of FRLG on Resort Gorgeous, to the north of Five Island, who will want to see some rare Pokémon, assuming you don’t take more than 250 steps before showing it to her before she’ll ask to see another one. When this happens, there will be a 5% chance she’ll give you a Rare Candy.
As per usual however, there’s a side quest attributed to this; you have to find her in the Lost Cave to the east of Resort Gorgeous (which is a headache to navigate), and defeat her in the battle. Only then is option B available.
Conclusion: it’s pretty long and tedious.
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