As per Hindu epics, a Maharathi is a warrior having mastery of all forms of weapons and combat skills. Maharathas are masters of all Vyuhas or battle formations and excellent strategists.
Mahamaharathi's: A warrior capable of fighting 24 Atimaharathi's simultaneously.This includes Lord Brahma, Vishnu, Shiva, Durga, Ganesha, kartikeya are Mahamaharathi's.
Atimaharathi's: A warrior capable of fighting 12 Maharathi warriors simultaneously.Ravan's son Indrajit is considered as a Atimaharathi who possessed all three ultimate weapons of Trimurti's.Parasurama the sixth avatar of Vishnu is also considered an Atimaharathi (as he possessed all three weapons of the trinity Pashupatastra, Vaishnavastra and Brahma astra)
Maharathi's: A warrior capable of fighting 12 Atirathi class warriors or 720,000 warriors simultaneously, circumspect in his mastery of all forms of weapons and combat skills. Kartavirya Arjuna, Lord Rama, Kumbhakarna, Lakshmana, Ravana, Lava, Kusha, Sugriva, Atikaya, Jambavan, Vali, Bhishma, Drona, Karna, Arjuna, Ashwatthama, Abhimanyu, Balrama, Lord Narasimha, Alambusha, Vrishasena (the son of Karna), Bhagadatta, Narakasura, Drupada, Virata, Jarasandha and Dhrishtaketu were Maharathis.
Atirathi: A warrior capable of contending with 12 Rathi class warriors or 60,000 warriors simultaneously. Kritavarma, Shalya, Kripacharya, Bhurisravas, Yuyutsu, Shishupala, Virata, Akampan, Satyaki, Drishtadyumna, Kuntibhoja, Ghatotkacha, all sons of Draupadi, Prahasta, Angada, Somadatha and Pradyumna were Atirathi's.
Rathi: A warrior capable of attacking 5,000 warriors simultaneously. Duryodhana, Sudhakshina, Jayadhradha, Dusassana, Vikarna, all 97 brothers of Duryodhana, Shakuni, Yudhishtir, Bhima, Nakula, Sahadeva, Uttar , Shikhandi, Uttamaujas etc were Rathi's.
Maharathi (warrior) Wikipedia
As per Bhishma in Mahabaratha, there are three classes of warriors: Ratha, Atiratha and Maharatha (in increasing order of might).
From Kaurava side
RathisSudakshina, the ruler of the Kambojas
Shakuni, King of Gandhara and uncle of Kauravas
Duryodhana's son Lakshmana and the son of Dussasana
Jayadratha, the king of the Sindhu and brother in law of Kauravas
All 99 brothers of Duryodhana including Dushasan are single Rathis
Duryodhana is classified as a warrior equal to 8 Rathis
AtirathisBhoja chief Kritavarma
The ruler of the Madras, Salya
Bhurisravas, the son of Somadatta
Kripa, also known as Kripacharya, the son of Saradwata
MaharathisAlambhusha, the Chief of Rakshasas
The ruler of Pragjyotisha, the brave Bhagadatta
Vrishasena, the son of Karna,
Asvathama, the son of Guru Drona, one of the eight chiranjeevi
Karna, is equal to 2 Maharathas.(But at the tale of Rathis and Atirathis, Bhishma classified him as just half a Rathi in order to prevent him from fighting against his own brothers Pandavas)
Bhishma, even though he never classified himself, later it was revealed that he is equal to 2 Maharathi.
From Pandava side
RathisUttamauja and Yudhamanyu Sons of Drupada
Shikhandi, the son of the King Drupada of the Panchala
Yudhishtira the son of Pandu and Kunti
Nakul and Sahadeva are single Rathis
Bhima is regarded as equal to 8 Rathas.
AtirathisSatyaki of the Vrishni race,
Dhrishtadyumna the son of Drupada
Kuntibhoja,the maternal uncle of Pandavas
Ghatotkacha,prince of Rakshasas and master of all illusions, son Bhima and Hidimba.
MaharathisVirata King of Virata Kingdom
Drupada, King of Panchalas
Dhrishtaketu, the son of Shishupala, the king of the Chedis
Abhimanyu,the son of Arjuna
Arjuna is equal to 2 Maharatha warrior