It will be outside, south facing so lots of sun on it, we also get lots of rain, so I need a black paint that will hold up to all that. The pots are currently a light tan color. What do I need to make them black?

I would spray paint them using an acrylic. It's not going to last forever. It will fade in the sun. Hopefully the pots will get annuals so you can re-paint every year.

well I was worried more about the paint sticking than fading. Like will it bond to plastic, worried it will flake/peel and not bond well? I have never painted plastic I guess!

It will say on the can

Keep in mind that black painted pots will absorb the heat more than other colors if you have them in sun and will need more watering.

I am thinking of doing something in it besides plants, like a fairy garden or a bird house or something like that, I just need it to look nice but I don't want to care for it

Krylon makes a spray paint specifically for use on plastic surfaces. I did a garbage can with it years ago. It held up pretty good. constant sun exposure will require a touch-up occasionally, however.

Rust-o-leum and Krylon both make plastic specific paints but beware of sticker shock!! Spray paint has gone through the roof. Home Depot had a great selection but anything other than the basic colors was well over priced. $15 to$20 a can depending on what you wanted. I needed zip ties-$22.79 for about 15-20 12inch ties.!!! Went to Harbor Freight and got a better size and more of them for $13.

Harbor Freight is the place to go for cheap tools and things. My husband loves that place! I used the plastic paint on a chair for my daughter. It has not peeled or faded in her strong Texas weather.