Hi,
the Czech
plural for Československý vlčák is
Českoslovenští vlčáci. I do not know it for sure in Slovak language, maybe Československí vlčiaci.
But be careful - Czech language is very difficult. Everything depends on in which sentence you want to use it.
For exampl:
Who? Czechoslovakian wolfdogs/Českosloven
ští vlčá
ci
With? S Českoslovens
kými vlčá
ky
About... O Českoslovens
kých vlčá
cích
etc.
Isn´t it funny?