first lets start with undyne undyne is the leader of the ryal guard and is asgores best solider she can also turn into undyne the undying she can summon spears and also throw swords at her foes overall undyne has great fighting skills now unto garent garnet is one of the gems from steven universe the only way to beat her is to defuse her and defeat her she has great powers that can use at foes in my opion i think Undyne will win.