If you bought the slowpoke tail in SS and HG?
It has no function except you can sell it for 4900.
source http://www.serebii.net/itemdex/slowpoketail.shtml
You cannot buy a SlowpokeTail in HG/SS without using cheats. If using cheats, you will be unable to sell it, seeing as it is a Key Item.
How to change your username How to add a user avatar Why was my post hidden? Question etiquette Flags vs Downvotes Anime FAQ Official PokemonDb League
Type a Pokemon name, type, move or ability to see instant results.