It all depends on when exactly the Brits are halted.
Going from major engagements after Plassey (seen as the start of the colonial British power)
Buxar- Mir Qasim removes all of their favoured status and they are returned to mere traders as he attempted and was the casus belli. From there he could either reform the administration of Bengal in line with the southern powers or accept Shah Alams offer to become vazir and reform the entirety of the area where Mughal power can still be projected in the gangetic plain. Even if he himself stays in Bengal, Shah Alam would have Awadh and Bihar under his direct control. The British attempt to place political residents in the Maratha court or the Nizams court and regain favoured status in Bengal. Mir Qasim could be a very good ruler of bengal-Mir Kasim was an able, vigilant and strict administrator. He had an extraordinary ability for the routine work of government. He had great enthusiasm for reform and efficiency. He showed great energy, perseverance and acuteness in overhauling the administration of his predecessors. He rehabilitated the finances. He reorganised the departments of revenue and justice. He created a new army on Western lines. He repressed the power of the barons. He not only worked hard himself but he knew how to make his subordinates work. He was an indefatigable worker. He was a clever judge of the character of those with whom he had to deal. ,He was a strict disciplinarian. He was feared by his subordinates for his merciless severity. He tried to remove fraud, corruption and negligence with a heavy hand. He enforced regularity and discipline with an iron hand. According to Ghulam Hussain, the Nawab was the most remarkable prince of his age on account of his skill in technical problems of administration and finance, insight into man’s character and motives, enforcement of a strict economy without appearance of parsimony and introduction of regularity in the payment of the troops. However, he was incredibly strict, and alienated many by forcing many of the richest inhabitants of Bengal to hand over their money to him.
Without the base of Bengal from which clives policy was slow and careful advance, never taking more than you can handle (though after Buxar it was militarily possible and was suggested, he declined to march to Delhi and make a conquest of all of India in the name of Shah Alam) it is possible that when the British relocate to their dominions centred around Masulipatnam they immediately try to carve out an independent state from the Nizams dominions, but more likely they focus on building Clive’s system of dual government in the Carnatic and attempt to puppet the Nizam of the Deccan as well as the Nawab of the Carnatic. They could probably take complete control over the Northern Circars and from there perhaps gain full control over the Carnatic and the Nizams dominions (although Mysore would always be looking to take the Carnatic and the Nizam was not only strong enough to prevent puppeteering but also vulnerable to the Marathas), but this is a weak place for attempting to spread authority throughout India- there have been much fewer southern empires which expanded north than the other way around and they are surrounded by the considerable military power of the Marathas and the Mysoreans. They would be opposed by the french advisors in Mysore, who may also spread to mysores allies/ the BEICs enemies such as the Mughals, Bengal, Awadh. There is a slight chance they could end up puppeting Awadh or the Mughals or Bengal after Mir Qasim but Mir Qasim and the Mysoreans are strong enough to prevent it happening to them and anyways french military power in India had been crippled after losing the Carnatic wars to the British and would have to be built up again at considerable expense through government intervention on the backdrop of the approaching French Revolution. The alliance which would probably emerge dominant would be Bengal/Mysoreans/Mughals/French and the way the British seek favour with these powers would determine the nature of their influence in the subcontinent.
If they failed to make peace with Scindia in the second Anglo Maratha War they could also have been halted by preventing the Treaty of Salbai. It was by means of this Treaty that without annexing a square mile of territory the British power became virtually paramount in the greater part of the Indian peninsula, every province of which with the one exception of Mysore acknowledged that power as the greatest universal peace-maker. Had the British not managed this, they would have been forced to carry out the earlier treaty of Wadgaon, under which they would have been forced to surrender some territory to the Peshwa and give hostages. It’s very possible that they would have been forced to pay Chauth to one or other Maratha magnate most likely Scindia himself. More important, they would not have secured peace with the Marathas for the next twenty years leaving them far less able to deal with the existential threat of Tipu Sultan to the south. Speaking of said threat, if Eyre Coote had not arrived, Haider Ali and his son Tipu could have taken Madras, as they even razed it’s suburbs otl. If this had happened they would have been left in effective control of the entirety of south India. From here, the British would likely be agitating for the Marathas and the Nizam to war against Mysore to re establish their southern possessions and weaken Mysore. Travancore, having lost such an important ally is unlikely to attempt its otl expansionism, avoiding the anti Mysore coalition of 1790. In the absence of Travancore trying Tipu buys the strategic fortresses of Craganore and Ayacottah If Travancore then realigns with the Mysoreans Tipu is Padshah of all of Sira Subah and stands a good chance of maintaining this as long as he can avoid a full coalition between all three of his major enemies. He would align as always completely with the french and would have very close relations with napoleonic France. Upon the napoleonic wars there is no doubt that war in India too would break out between those aligned with the french and those aligned with the British.
Another opportunity for halting Britain’s rise is if after the third Mysore war, they partition Mysore completely between the Marathas, the Nizam and themselves- the reason they didn’t do this otl though they could have and it was a fairly popular idea among the critics is that it would empower the Nizams and the Marathas too much- following the later deterioration in relations this could have gone wrong.
If you prevented the government of Lord Wellesley, you prevent the development of the system of subsidiary alliances that turned Britain from one among a few of India’s regional powers to the paramount power, and their relationships with other powers stay more like traditional foreign diplomacy than colonial rule. If the Nizam had not accepted the subsidiary alliance or disbanded his french trained army before the fourth Mysore war, this could have also prevented British domination of Hyderabad .Many critics have condemned the Fourth Mysore War as unnecessary and unjustified. It is pointed out that the French danger was needlessly magnified by Wellesley. There is a lot of truth in this criticism. Wellesley was a full-blooded imperialist to whom Tipu was a formidable hurdle in the expansion of the British empire in Southern India and consequently the liquidation of Tipu was a top priority in his political calculation. Wellesley knew that with the disappearance of Tipu from the political scene, the steamroller of British imperialism would be able to crush very easily any opposition from the Marathas. The Nizam was too weak a power to create any difficulty. Wellesley considered Tipu as the real enemy of the British and hence took action against him. Otherwise, there was no moral justification for the war.