In Ben 10,000, Ultimos still has his powers, but this is in an alternate timeline, meaning that Vilgax never stole his powers or he did and Ultimos recovered.
Ultimos using his Freeze Breath
Ultimos using Heat Vision
Ultimos's weakness is chocolate. It turns his skin to a brownish gray color, makes him cold, shiver and collapse, and becomes skinnier when eaten. Synaptak identified that a specific chemical in chocolate is poisonous to Ultimos and his species.