looking at the image i like it. Base/Omnitrix form is clearly bassed on Kaixa and Decade- at least that's how it looks to me. Heat blast is what Ichigo/Nigo Way big was that J or ZO that was the giang rider- i can't recall.
As for the others I can't really place riders where inspiration may of been drawn from. mainly because Ghost freak and ripjaws are so small, it is hard to make them out. And I can't really place either Diamondhead or XLR8.
Well I'd say that the visor is more straight off XLR8, so with it just being a helmet its hard to tell. The Decade/Kaixa bit of the omnitrix form was based on body/helmet. The chest armor makes me think Decade, the helmet looks to be a recolored Kaixa helmet. And the Heatblast looks like Ichigo/nigo "The First" version.
I don't wanna say that XLR8 is Kiva based just off the XLR8 visor shape.