It's really comes down to how they strategies a TM will get all abilities,skills experience and potential future abilities plus there weapons as well. Rimuru and Anos are used to this. But let's be honest the only character that can easily one shot a Experienced TM is Altair that's way no body ever really mentions her in these posts
There are several fictional characters that can beat an experienced Total Mimicry, but the wiki here would say stuff like an Experienced TM user would beat One Above All or Presence and perhaps Sun Wukong.
Total mimicry can mimic nigh-omnipotence no problem but it can't mimic true omnipotence like the true God's of each verse like the presence the one above all sun wukong I'm not completely sure he achieved true omnipotence I really don't. But I say TM don't beat wukong.
Nigh-Omnipotence characters like Cosmic Armor Superman, Lucifer Morningstar, Oblivion, etc. Yeah, but I'm questioning why some users here have a mindset of "Mimicking someone's superpowers = Automatic win" or something like that.
That's what make TM so dangerous it's not just the abilities and skills it's because you can mimic experiences and there mindset completely and memories
Total Mimicry in media is often displayed as.. mimic superpowers whatever you see (Looking at you Medaka Kurokami and Protege.), but I've never actually seen a character who can use Total Mimicry to not just copy superpowers but copy transformations, memories, etc.
I hate to be the guy, when having a conversation with buddy here a week or two ago. But think about how experienced the mimicry user is, do you think he might have the intelligence to think of the best parts to mimic?