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Not really.
Tiers were never really that accurate to begin with. The only real shitmons are things that are either slow and weak or just unviable - you know a shitmon when you see one. As long as your favourite Pokemon isn't Sunflora or Dunsparce or whatever, anything can be used with the right investment and the right moves for whatever circumstance you may see fit.
Gastrodon for example is an RU Pokemon, yet it's actually not uncommon in OU. Why? Because if it's not a Grass type or a sweeper that has already set up, Gastrodon walls it. People even use it in fucking Ubers to wall Primal Groudon and other shit.
It really depends on what your favourite Pokemon are. I happen to be quite well off since most of my favourites are UU or OU at best. Pic related - people think he's shit because "DUDE ICE LMAO" or because he isn't Blaziken or Swampert, but few people realize he works fucking wonders in OU: perfect counter to Rotom-W, OHKOes Scizor with HP Fire, can check Azumarill, Latios, Hippowdon and all sorts.
Bottom line: as long as it's not NU / PU garbage (you'll know a shitmon when you see one), it can be used.
