I am an old/oldfashioned pony lover.
ONLY G1s - after that..........Nope!
I have had just about every one - Nirvanas included.......Rapunzel, Mermaid amd a couple of others haven't had/got from the finance point of view.
I am downsizing them slowly - it is hard to know who to let go! 

I have had a lot of success with simple sun-fadng.  Sometimes not even covering their hair or symbols. The trick is not to leave them on one side all the time..........I ended up with nearly white on one side pink pony cause she was in the STRONG sunlight too long.

As for age spots! People get age spots - some can be removed - some can't! Breakdown of the plastic is also almost impossible to fix.....especially pink ponies - they can look as though they have chickenpox or something.  Clever people can re-paint the pony but eventually the breakdown breaks though again.

Mould can be dealt with and various things will help - like a good clean inside and out and usinng some ordinary mould remover. Just depends on the pony colour too - white is easy but some of the coloured ones, the mold will go but also the pony colour will go lighter

Trial and error!

Have several versions of her - she is purple! What's not to love? AND of course here unique sitting position. She is lovely - we would BOTH like to be at the sea side in the sea shells! 

Have this girl and her sisters too. Cute set and most still smell nice too.

I have her - sorry no photo - but I love her pose and her golden hair. One of the original and the best?? 

Had both these ponies for ages but have to dowbnsiz my collection so they went to nice new homes!

Very hard decision who will stay and who will go!

Did not have her.Not a G3 collector any more have sold or given away most of them - just sticking to G1!
Too many ponies!