Fire should be able to break blocks with Combustion, and not Fire Blast, neither Fire Burst.
My suggestion is to use the most explosive moves instead of the most powerful ones.
FIRE -
Combustion, Lightning, & charged Fire Blast
I don't see any Air moves in the PK plugin being able to have the power to break blocks.
Water, not Surge because it is a wave, not a blast.
so for Water I suggest:
WATER -
Ice Blast
I can't think of any :L
Earth, Lava moves should break blocks, and Shockwave should leave a corrupted path
This probably wasn't a big help xD
Although I don't really like this idea because GRIEF, but I don't think Ice Blast should be able to break blocks, I think torrent should, if any. Hama used it to slice a rock in three.
Also, I disagree with your comment on air because Aang has shown many many times capabilities of breaking structures. Like when he went to the Northern Air Temple, he practically blew a wall open and tons of equipment and sent them flying across the mountains. He also used it to blow open several doors through out the series. He's also pierced a giant meteor into little bits of dust when he was facing a Fire Nation blockade.
Finally, as for Earth, I don't think earth abilities should be able to break blocks, but I did have an idea of a suggestion for Earth that I was going to make eventually but was too lazy for; the move is "Rumble," similar to what Kuvira did against Korra in the latest episode, she caused a rock to crumble and explode in Korra's face. The suggestion is sort of like Lava Flow except when they click on Earthbendables it's not lava, it's just a bunch of dirt particles and blocks breaking and causing small damage and knockback to anyone who's got trapped in it. This would also be able to block Earth Smash, Earth Blast, and destroy Earth Walls. Also, I'm not really sure but I could also see this crumbling a PART of Shockwave, how shockwave is an ever expanding ring, this move would create a small opening in the ring.
One day I'll actually make that Earth suggestion, I hope, or someone else will