I am not entirely sure what you are attempting to articulate. If you are indeed implying that Mewtwo and Lucario are clones or too similar, thus making it impossible to have both on the roster... I have to disagree. However, if you mean that Lucario replaced Mewtwo in essence, I most certainly agree. It is certainly a fairly subjective notion. I am going to have to use my fancy latin on this one. Res ipsa loquitor (the thing speaks for itself).
For me, whether or not two characters are clones has no factor on me thinking they'll be in the game or wanting them to be in.
I do however believe that Lucario replaced Mewtwo, because...y'know that part where that was exactly what happened. I see the characters as quite similar but not to the level of clone status.
An old fools perspective
Link and Young Link are clones. Toon Link is... Similar. something better to some people, something worse to others
Fox and Falco Melee are clones. Falco Brawl is similar. Refreshing to some [like me] disgusting to others [not naming names]
Wolf is the third category. just something... else.
I see way too many similarities, undoubtedly more than are actually there. Might I ask what two moves do every one else see? I suppose I should quote Arcanir... The popularity of the character outside of the game at the time, the little attention to detail with the effects of the attacks. Like I said, I undoubtedly may have the incorrect perspective. The undeniably WRONG mindset, but that's just the way I see it arcanir. The colored flames the shadow ball the up tilt.
they're far enough away that they can't be considered clones. but it also seems to me, is this the furthest apart two characters can be designed away from each other? maybe it's because mewtwo wasn't there, maybe they designed it that way to trick angry old fools like me. I don't know. so i'm willing to disagree, i personally think they look alike, but i'm ok with being wrong there.