I'm maining Tanya (among others) atm, and in my opinion she's the best character in the game right now, hands down. And I do think, even after her recent minor nerf, that she's still too strong. My argument's pretty simple: mobility is everything in fighting games.... and hers is not only the best, it's the best by a large margin. I honestly think she's on her own tier at the moment because of this.
Look at any fighting game and look at the very best characters and note what their strengths are relative to the rest of the cast. It's always their ability to manipulate their mobility, or their ability to restrict their opponents mobility, or both, that make them the best. If you can't dash or unfly in MvC2, or if you can't jail your opponent like Strider, or if you can't kill your opponent for pressing a button (Cable), or if your assist option doesn't stop your opponent in their tracks, you're not even in the conversation. Look at MMH in Injustice: air dashes, teleports, long-limbs, projectiles. Evil Ryu in Ultra, O.Sagat/Dhalsim/Vega in ST.
Who can compete with her mobility? She can advance backwards and forwards with invincible frames and not spend a bar of stamina. Even if all of her other tools were trash tier, she'd probably be middle tier on her teleports alone - throw in the fact that she's a solid character without them and you have a very strong character that you can't just "figure out" in a few months. Of course predictable scrubby Tanya's are going to get bodied for tele abuse, but that's not what I think about when I think about this incarnation of her being the best character in the game months down the line. I'm thinking of polished intelligent players always holding the advantageous position against their opponent because Tanya's toolset is perfect for keeping the higher ground all day.
With that said, I don't want her nerfed into the ground. I love this character and she's my favorite to play, but I know how good she is and how NRS works - she will get nerfed, this conversation and character defending and attacking isn't going to prevent the soon to be obviousness of her strengths and the inevitable response from NRS. IMO, I think the only constructive conversation is one where players who main Tanya admit that she's too strong and try to find solutions (aka nerfs) that aren't damning our main character, while still keeping her relevant in the future meta.
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TLDR, Tanya mains: she's going to get nerfed, stop pretending like she won't, and let's collaborate a reasonable nerf list that keeps her alive so we can continue to enjoy her in the future.