Recently came back to the game, mostly due to losing most of my progress to incorrect merging way back when silver and gold servers opened, kept my yellow server pokemon but had to start collecting badges over from the beginning.

That's on me and probably not that difficult to get back to where i left off, but I just noticed that pokemon I had fully evolved (Starters for example), only the final evolution counts as caught, previous evos as either seen or unknown, is there any way to tick them retroactively or am I off to look for a new charmander?

Hello, Thank you for reaching out to us and sorry for the inconvenience that may have caused.
 

If you want to, we can re-merge your account correctly, but, if you do any trades on your account, that wouldn't be possible anymore.

About the evolution data, we cannot do anything about it, since the account was merged incorrectly, you would have to get the "caught" and "evolution" data again.
 

Looking forward to your response.