Can I erase Probopass from existence for looking absolutely ridiculous? It's actually a decent Pokemon, but I could never find myself using it just because of its design.
The only other Pokemon I think I might erase is Heatran. Gen IV really felt like it started to add more and more legendaries just for the sake of it, and Heatran is one of those in my eyes. I almost considered Regigigas, too, but at least it has some connection to other legendaries, unlike Heatran, who's just kind of there.