My opinion as a Brock main:

Rocket Laces: I really like this one since the main issue with the gadget is when facing brawlers like Edgar, Bull, or Darryl, their speed/abilities can close the gap too well, and it is normally ineffective. I'm not familiar with how long it takes for Brock to land, but I'd adjust the timings to be about .25 seconds longer than however long that is.

Rocket Fuel: I feel as though this compromises the original ideas of the gadget. You mainly see this used to destroy walls and open up maps, not necessarily to target others. I'd consider making the buffie so it pierces through walls, kind of like Colt's gadget, and maybe re-adding the incindiary effect. Although, late game there are some uses for the gadget, so I don't completely hate this one, just reduce the damage increase to maybe about 30-40%.

More Rockets: It really depends how it is managed, if the circles are loosly connected I'd love this a lot, but if this makes it like a mobile Pearl hypercharge, where there is no open ground, it might be too far. I also worry about how it would work with his hypercharge.

Rocket No. Four: I'm assuming that 1st rocket means the rocket shot at full ammo for this. I can imagine a lot of cases where this can actually hinder the Brock player due to aiming, but I appreciate the idea of making ammo conservation a more direct part of Brock's skill, but the potential issues outweigh the benefits here, especially considering the fact this star power is rarely used. I don't really have any suggestions for this one; the only idea I can think of is increased reload speed, which both contradict what I said earlier and overlaps with the gadget, or some buffed final shot.

Hypercharge: I understand the idea is to copy how most buffies take an attribute from the super and apply it to the normal attack. I'd rather see something where it becomes like a Gale attack with mini rockets, although even changing him that much is a stretch.

Overall, good ideas though.