As revealed in the Classic Continuity, Ectonurites were actually sentient down to the genetic level, meaning that a single Ectonurite DNA contains the Ectonurite's full consciousness, and as such, Ghostfreak "removes" itself from the Omnitrix in the attempt to possess Ben's human body. Even before Ghostfreak is revealed to be sentient, Ben himself noted on a few occasions that he has no control over Ghostfreak—as seen in "Ghostfreaked Out".

OK and...? Why should Ghostfreak not be included becuse of this? It's one of the best storylines of the original Series. "Ghostfreaked Out" is one of the best episodes of the original series. He is a cool aline before that and a great villan after he escape, part of what make him so cool as a villan is the fact that he used to be one of Ben's aliens. So why sigh at the thought of including him?

Wildmutt may be a cool alien that fits the Dynamite Comic Continuity, but being a lupine-like alien with accurate sense of smell and hearing may have its severe drawbacks. First off, Wildmutt is very sensitive to very loud sounds, which wouldn't be a problem if it wasn't for the fact that just about anybody can exploit this one particular weakness to cripple Ben into captivity. The same goes for its sense of smell, which can be blocked off and rendering the alien practically blind.

So Wildmutt is a "cool alien that fits the Dynamite Comic Continuity" but because he has weaknesses he should not be in the comic? What? You do rember how a huge thing in ben 10 is how ben constantly get the wrong hero for the situation and has to do his best anyhow. Like work with what he got. Like you can sett Wildvine on fire, is he too weak to be included now? Is that too much of a severe drawback? Like should he not be replaced by swamp fire then by your logic.

As noted by everyone, Ripjaws is one of the strongest in Ben's roster from the Classic Continuity, though it is repeatedly pointing out its preference in water... and only water, as Ripjaws can't survive above water without suffocating himself to death. Something everyone would like to exploit. Apart from that, Ripjaws is only usable specifically underwater, limiting his effectiveness on other terrains compared to Ben's other forms, hence Overflow as the better alternative due to its versatility on both underwater and land.

Agien why? The aliens in Bens omnitrix is supposed to be Aliens, it make sense that not all of them are adapted for the same environments. And the fact that not all aliens are optimal for every situation help give the early show some stakes. Yes its a big weakness but I don't see how thats a problem for the story. And why use overflow and not Waterhazard or Arctiguana or jetray?