When A male lion takes over a tribe he often kills all the existing cubs. How does he get past the protecting lionesses to do this?
The lionesses will often try to defend their cubs.
In some cases a coalition of young related males will take over the pride, and clearly this helps in dealing with irate mothers.
No sign of the mother though in this video where a lion is filmed efficiently dispatching three young cubs.
IIRC from some nature show or other, if the young are cubs the lioness stands with their father to try to drive off the newcomer, but if they’re old enough to stand a chance on they’re own, she’ll hold back and leave the alpha male on his own. If he loses, the young males will flee and begin a solitary life on the plain until they’re mature enough to make a bid for their own pride.