machamp vs tyr

at level 36, counter deals 16 damage, up from 15, assuming 15 attack IV. 1 extra power up for each point under 15.

counter deals 15 damage at 27.5, but powering to 30 is still useful for more HP and defence breakpoints, or breakpoints against other bosses.

Edit: Didn't see any answer yet. Above answer correct.

Here is one from SR with near all the raid bosses (minus Articuno):

https://www.reddit.com/r/TheSilphRoad/comments/6r4tee/info_various_raid_counters_damage_breakpoints/

...deleted...double posted.