Smash Ultimate Tier Lists - Age Chart

Ken is at LEAST 20 years old-- and could be older depending on what point in the SF timeline he's been pulled from.

Marth and Lucina need to be bumped up a tier. Marth's based on his older Mystery of the Emblem self, and Lucina's the same age as Chrom- not to mention pulled from post-timeskip Awakening.

And Ness and Lucas are canonically 13 years old, and as such should be moved up a bracket; Ness is only days away from 14 by the end of EarthBound, in fact.