Well, that's definitely true, and I agree. Lip 4 Smash, plz.
But still, Metroid [and DK] are still pretty lacking in representation despite being big classic series that have been around in Smash since the very beginning.
I'd say DK (currently) has more of a raw deal, though I can at least understand somewhat why that'd be what with Rare and all pre-Brawl (though it doesn't excuse Sakurai not even thinking of the classic DK Jr. as a clone option in Melee).
With Metroid, it hasn't done too bad, all things considered.
-Yes, the only playable characters so far are Samus and Samus without her armor, but other than Ridley, Metroid doesn't really have any characters that are
both major and viable. Except maybe Dark Samus, but she's an Assist.
-Metroid has
three Assists now, which is currently more than any franchise that isn't the big names Mario and Zelda. And it was going to have two in Brawl, which would have been a big deal considering only Mario had more than one Assist then.
DK currently hasn't been shown with one, and didn't have one in Brawl.
-Metroid had not one, but
two bosses in Brawl. More than
any other franchise (unless Pig King Statue counts). Yes, they were both Ridley, much like both playable characters for Metroid were Samus, but still.
At least Metroid's most iconic villain plays a role in the story. DK's iconic villain was nothing but a trophy.
-Currently, Metroid has four enemies featured in Smash Run as opposed to DK's two. Admittedly, it's not much compared to other franchises (including Smash itself), but it's about the same as Pokémon at this point. Though there's supposedly Kraid and a "large Kremling" to consider...
-Stage-wise, Metroid's generally averaged out with the rest of the franchises, but in Brawl, Metroid has three stages featured, which is tied for second most alongside Donkey Kong, Pokémon, and Zelda. Mario was first with a whopping
6.
As for Smash 4, we've seen only one stage for each so far, but Metroid's is a new stage while DK's is a returning stage from Melee.
Though no one really cares about that; they just care about the characters.
As much as it pains me to say it, unless the franchise adds more characters that are both major and viable, Ridley would be the last character it gets in Smash.