According to the pet tool if I fuse 70/70 rare pet for 70/65 i will get legendary 70/67 pet. The exact same result is promised for 70/70 + 70/64 fusion. So I wonder, will the legendary pet get 67th level of 2nd ability partially maxed or will it be exactly at 0 (I mean, at the beginning of the 67th level)? If the first case is true, then how many feed power will the 2nd ability get after the fusion?
No, the new level will not be partially maxed.
I fused 70/65th pet (as target) with 70/70th pet. First had 36452 points in it's 2nd ability, second had 57840 points, this makes the average number of points 47146. But the result was 70/67/1 pet with all levels at 0, so 2nd ability had only 39921, according to the value of 67th level.