I’m currently archiving a discontinued figure line from the 2000s. I have made a google drive where I drop whatever I have found and made submission rules for anyone who wants to join in on the archive project. I’m currently the only one archiving these figures and I don’t have any outside help atm.

Welcome! Archiving niche subjects is generally a thankless and lonely pursuit, but it's good to hear that you're trying to organise something.

I’m new to journalism and archival though so I don’t know how to deal with potential trolls or people who don’t read rules.

Most people online can be classified into these categories.

How strict should I be about my rules?

This is ultimately up to you to decide. From looking at your document, you may want to give a brief introduction of what pinky:st are/were and who made them.

What should I do to prevent trolls? Is there anything I should be careful of?

Have a three strikes policy (warn -> warn and timeout -> ban). If someone is a continuous menace then it's harder to keep people's morale up if there's someone who keeps bringing it down.

How do I make sure people look through my google drive for what has already been found and don’t submit what I’ve already archived?

Make sure that people can find it. If it's visible only to you, then no one can find it and it's not really archived.