Yeah, I know that any character can be used as a basis for any other: the thing that really caught my attention with Ness was just like what
Spatulo
mentioned: stuff that no other character has / have the closest possible thing that can be used (We have 2 whip characters, but they used Simon because they served better for Byleth's Moveset). Also, I consider these glitches that weren't there at 1.0 as someone tampered with the character between updates. Aside from balancing, why would you tamper with a character, unless something about him was being used in another place?
The things that caught my attention about Ness being related to Geno were:
- The Normal Special, which is a attack that is charged by holding the button and you can release it any time, just like Geno Beam.
- The Second Jump, which is a really floaty jump that has a magical feel to it, and could work very well with the fact that Geno is a Star.
In general, every new character we've seen from DLC is a base character with a mix of 2-6 others + new stuff that can't be reused: some for animations, others for gameplay properties (which is what put the Ness glitch on my radar).