I... I just OHKO'd Nuclear Actan...

[Dragonstrike]

Isn't this the one where Theo's dialogue is a red herring and you can't actually catch it? or did they change that?

1.2 Patch notes mentioned this:

Bugfixes:
...
* Fixed bug where you could catch nuclear Actan only to lose him afterwards.
*...

Nobody ever confirmed nor denied in the thread if you could actually catch N-Actan again, either...Windos and I interpreted it as being able to catch it again for the first time since the first major update Uranium had, but I don't think anyone's said anything about actually catching and keeping it in 1.2 here nor on the subreddit so far.