Which item should I use instead of Miracle Berry in Pokemon Stadium 2 Little cup?

Solution 1:

No item is necessary in Pokemon Stadium 2. In fact, you can use a team with no items - all the rental Pokemon do not use items, and at least all of R1 has been cleared using only rental Pokemon.

Miracle Berry cures any sleep. This makes it better than any other status berry such as Mint Berry in most scenarios.

I don't recall status being particularly common in Little Cup. Excluding those you have mentioned, the choice of another item is opinion based. My two recommendations are a matter of consistency vs "low chance, high reward":

• Magnet. If you're going to use a type-boosting item, using the one of the same type as your STAB is generally optimal. This is my preferred choice. It's only a small boost though
• Focus Band. This gives a small chance to avoid a KO. Only a small chance, but that chance can potentially give you an extra attack that can change the match outcome.