Meowth's time has definitely come and gone, and while I frankly didn't expect it to ever happen pre-Gen 9, Ash and by extension Team Rocket bowing out of the anime is pretty much the nail in the coffin for Meowth in Smash I think.
The anime was about all that was keeping Meowth relevant to the franchise, since it had a specific unique member among its ranks, but in Smash the only time Meowth has been depicted as that incarnation is his trophy in Melee, which depicts his appearance in the Meowth's Party tech demo (and technically the ending to Pokemon Channel's Pichu Bros. short, but that came after).
Any time Meowth appears as a Poke Ball Pokemon, it makes no vocalization at all I don't think, let alone actual lines, sort of like how Electrode has never said its name or anything as a Poke Ball Pokemon. It was never based off of the anime as a Poke Ball, but the long running stint in the anime as Pikachu's rival kept the dream alive, but even that's gone now, so... Not looking great for the Scratch Cat.
Eevee kinda has some things going for it, but I feel like to make an interesting moveset, you'd have to either specifically make it Partner Eevee from Let's Go, or it'd have to be a relatively standard moveset with like... Extreme Evoboost as basically an install super or Gmax Eevee, and Extreme Evoboost is two Generations past now while Gmax is one Gen past lol