Feel free to post test results and request battles and customizations. Here are some tests that I did. (All BEYBLADES are stock combos. 5 rounds each. Battles in the SlingShock starter stadium. All BEYBLADES in battle ring mode.)
Kerbeus K3 VS Valtryek V4
(K3 5 survivors VS V4 nothing)
Kerbeus K3 VS Forneus F4
(K3 3 survivors VS F4 2 survivors)
Kerbeus K3 VS Achilles A4
(K3 4 Bursts, 1 survivor VS A4 nothing)
Overall I think that Kerbeus K3/K4 has Bad attack, O.P. Defense, Decent stamina.
Kerbeus K3 VS Valtryek V4
(K3 5 survivors VS V4 nothing)
Kerbeus K3 VS Forneus F4
(K3 3 survivors VS F4 2 survivors)
Kerbeus K3 VS Achilles A4
(K3 4 Bursts, 1 survivor VS A4 nothing)
Overall I think that Kerbeus K3/K4 has Bad attack, O.P. Defense, Decent stamina.