The Undying (Pokemon and Undertale crossover)
For a millennia the legendary Pokemon Dialga, Palkia, and Giratina have been warring over who is the strongest of the three. Only few knew of the fight within another dimension and knew how to halt it. They chained Dialga and Palkia, allowing Giratina to remain free and keep balance.
Then, one fateful day, Palkia is freed.
Almost immediately the balance between time and space is turned on its side as timelines are changed throughout the dimensions.
Ash Ketchum has done extraordinary things in his life, along with his companions, Serena, Clemont, and Bonnie. But he isn't prepared when the timeline transports a new character into the Pokemon World. Now, with the universe and dimensions falling out of proper alignment, the worlds need a hero. They need to be saved, by the character who wanted to destroy them.