Anime war is a fan fiction on youtube created by "MaStar Media" And is about characters from different anime teaming up to defeat evil gods wanting to control the multiverse. The series is popular mostly because it's the origin of the fan transformation "Omni super saiyan A.K.A Super saiyan white."

The story starts with goku fighting saitama and saitama pushing goku to super saiyan blue kaio-ken x10 but the fight got ruined by vegeta. And goku black would appear wanting to fuse with goku so they can kill zeno and it being found out that goku black was created by evil gods from universe 13 called "Mai-kaioshin realm" and goku and saitama would try to beat goku black but once goku black turned super saiyan white they couldn't but once vegeta was revived, vegeta and goku fused into gogeta and they went super saiyan blue kaio-ken and when they were about to kill him they defused then saitama killed him using the attack "Big bang dragon fist." After goku black died the evil gods managed to escape universe 13 and into universe 7. Goku would fight the leader of the evil gods but he was too strong and when he fused with the others they turned into a black version of cooler with red highlights called "Archon"

After archon killed whis goku would stop beerus from killing him just so he doesn't die and then zeno would appear and his guards would fight him but wouldn't beat him and zeno would absorb them and turn into true form zeno.

And archon would go ultra instinct

Goku would prepare the multiverse spirit bomb which is created from infinite anime dimensions hoever due to the power of such a move goku would need to fuse with vegeta and saitama.

However you can't watch the original series anymore because it was removed because of copyright but you can watch reuploads of it. Here is a link to the best one I could find (By the way it's 4 hours long.)

https://youtu.be/u2zxYvzZmL8?feature=shared