On the idea that Isaac isn't unique, let me tell you something: There are dozens if not hundreds of ways to theorycraft an Isaac moveset. Don't believe me? Here's one I made that covers every possible detail for the character, plus Felix, and it gives him an axe with a focus on elemental physical attacks.
Link here:
https://docs.google.com/document/d/1GtHfg_IsSA5BdXg0k-LRpDzKDcuDr1upA2E0Kh808Yk/edit?usp=sharing
There's a lot that this character can do, basically. And nobody else could be quite like him. (shameless plug is shameless btw)
Anyway, there was a discussion earlier about our predictions and maybe wishlists for the rest of the roster? I'll give my prediction, with one wishlist item sprinkled in:
Number 68: Geno
Number 69: Isaac
Number 69e: Felix
Number 70: Skull Kid OR Bandana Dee OR Decidueye
This would round out the roster at an even 70 by the Sakuraicount, which is a nice way to end it when this installment is so numbers-oriented.
Remaining Echo Fighters:
Number 5e: Yarn Yoshi
Number 14e: Dry Bowser
Number 36e: Dixie Kong
Number 38e: Shadow the Hedgehog
Number 64e: Octoling
And the one that I REALLY want to see but I know probably won't happen:
Number 11e: Blaziken