Be careful what you wish for...

[The Elf-warrior]

I wish Tulkas would have come and challenged Morgoth to single combat so Fingolfin wouldn't have to die.

Your wish is granted. But Tulkas fought without a sword and was sliced and diced by Morgoth. The Valar were enraged and did the War of Wrath years early. Earendil never became a star and so Galadriel gave Frodo a flashlight which didn't stop Shelob from eating Frodo and Sam. Gollum only had his Precious a few days before a Ringwraith found him.

I wish Gollum had repented and confessed that he was leading the Hobbits into a trap.

Note: Ralph Bakshi is a director of mostly animated films. He made an animated version of Lord of the Rings which was supposed to be in two parts but the second part was never made. link