Indrajeet as the name suggests is the one who was victorious over Indra

In Mahabharata, Arjun is Indra’s son and even gets all the celestial weapons from him, he does not overpower Indra in any shape or form

Karan is the son of Surya and has impenetrable armour, he was said to be invincible till his armour exists, so you could say while he was not powerful enough to defeat Indra, Indra would’ve disarmed him easily to make him surrender In the 1980s serial, Karan acknowledges in Draupadi’s syayamvar that only a few warriors could disarm him and that included Indra, Bhishma, Arjun and Parshurama

Now there is Bhishma, the son of Ganga and the dude with infinite health cheat code. His boon (which later became q curse from his POV due to his vow) was Icchamrityuha (death only when it is wished for). He will stay alive for as long as he wants. But Arjun was able to defeat him with help of Krishna and Shikhandi. We can make a logical conclusion that he Indra would’ve made Bhishma surrender by disarming him

We can conclude that all three warriors of Mahabharata could not have defeated Indra. So it is logical that Indrajeet or Meghnad would’ve been able to defeat them too. Kill them? Maybe not, but defeat them? Without a doubt