For me it’s the L30 tryo that I worked forever to get to that level. It used to be a good tryko counter, but now that I’m up against faster trykos that do 5000 + first turn damage (with crit, which always happens EDIT: That’s strike + counter attack - for the pedantic.) it’s just pointless, and I didn’t want to put my boosts into it.
How about you? Anything made useless by boosts?