"Number 79: Battlin' Boxer Nova Kaiser" Rating Score by シエスタ

It doesn't have a specific material, but it has an effect related to BK, so it's mainly used there. It is an advantage for BK that it is easy to cooperate with general-purpose monsters.
It has a material replenishment effect targeting BK, and is strengthened by the number of materials.
However, since the reinforcement rate is low and the raw RBI is not high, it is doubtful whether it can be relied on in terms of battle.
If destroyed, you can revive as many lower grade BK as the number of materials, there is no condition like "X summoned", and there is the aforementioned material replenishment effect, so it is effective for resurrection and irregular summons.
However, it is hard to say that this is also easy to handle because it is limited to destruction from the opponent and depends on the opponent.
If anything, I want to connect it to a combo using X materials.
If you use the Cestus that fell in GY as a material, you can aim for the additional effect of Caestus from RU, or fulfill the shadow conditions.
It is hard to say that the unit performance is excellent even in flattery. I think it will shine if BK-related products that are more compatible with materialization come out, so I would like to expect more in the future.