Well, they may be very not thought of before.
-Dragonball Z/Elfen lied.
It came a fanfic called "A saiyan's past" by solar rinstar. A retelling of the elfen lied storyline but has only Gohan and goten.
-Slayers/Pokemon.
I dont know why, it came out of my head randomly, maybe because I want to see lina's interations with pikachu.
-Inuyasha/Beast wars 2.
Must be an anime reason I guess.
-Evangelion/Transformers.
It tells us why the Transformers are robots in the first place.
-FLCL/Transformers animated.
You tell me how it might be like.
-Gurren lagann/Transformers animated.
action, and Yoko and Bumblebee partnership.
-Darkstalkers/Spawn.
very related.
-Kingdom hearts/Soulcalibur.
think about it, but with sora only in the past teaming up with siegfried.
-Godannar/Transformers.
Imagine seeing Optimus prime combing with godannar.
-G-Gundam/Gundam SEED/Transformers.
Star convoy FTW I guess.
-Inuyasha/Kenshin.
VERY simmilar attmospere.
-Inuyasha/Slayers.
If you like this idea beter than the Beast wars 2 crossover.
-Dragonball (First one)/One piece
I liked ths idea better than the DBZ/One piece.
-Nausicaa/Evangelion.
Some random idea.
-Ponyo/One piece.
Some random idea.
-Nightmare before christmas/Soul eater.
Some other random idea because of the realated atmospere.
-Code geass/Transformers.
Random cool thoughts, and it's mostly armada continiuty.
So tell me what you think of them and tell me YOUR crossover ideas.