Help - I to start new game but have too many pokemon.

Want: Start authentic Pokémon Platinum all over again.

issue: Pokemon Platinum contain 300+ Pokemon and i don’t want to overwrite current progress.

Have unmodded consoles: 2DS, 3DS, Dsi, DS Lite

Have authentic games: Fire Red, Leaf Green, HeartGold, SoulSilver, and Pearl. these games made it far enough to at least trade.

Solution: Idk. trade 6 pokemon at a time? sounds super time consuming. rather not do that.

thoughts?