Hello Here is another Idea this time I come with the Ideas for mechas I might make a list of possible mechas series that might be able to mix in the dxd verse
The Escaflowne: Why I put this mecha? Simple because the mecha mix perfectly in the magical world of DxD It doesn't need a special fuel of another world to use it you just need to power him using the blood of the Pilot. The Mecha appearance has two forms the normal one is that of a Knight and the other one Dragon Form giving us the idea that might be built to fight dragons.
The Idea for the Plot: What if the Vali team fined the escaflowne in the dimensional Gap and brings it with them to their base of operation.
Nobunaga The Fool: This one I don't have many Ideas for it but it mix a bit since the Regalias are magical they could be mixed with DxD
The Idea for the Plot: I don't have any Idea for this one
Multiple Series Mecha Crossover:
The Idea for The Plot: Many Mechas that were destroyed in their original series are falling from the sky completely unharmed
AN:
Now Why I didn't say evangelion because there are already crossover of that mecha series
Another thing is I am writing my 1st own fanfic maybe it will be a One Shot until I grab the trick to this.
Recommendation: 20th Century Boys by Naoki Urasawa the villain of that series is very intriguing like Johan Liebheart
And Sorry for My Bad English plus Gramamar