WARNING: The following article contains spoilers for Dragon Ball Super Chapter 51, by Akira Toriyama and Toyotarou, available now in English from Viz Media.
Dragon Ball Super Chapter 50 saw the tide of battle shift against Goku, Vegeta and Buu when Moro revealed he used his final wish from the Namekian dragon, Porunga, to free all of the Galactic Patrol's prisoners, effectively giving himself an army. Goku used Instant Transmission to teleport himself, Buu and Galactic Patrolmen Merus and Jaco from the battle. However, Vegeta opted to stay behind and hijacked a ship, directing it to planet Yardrat, which is where Goku originally learned Instant Transmission in the first place.
Chapter 51 sees Moro's forces ravaging various planets, with each excursion making the energy-absorbing villain stronger and deadlier. Vegeta spends most of the issue traveling to Yardrat, though he seemingly reveals his plan only really consists of going to the planet in the hopes that they might know something he can use. Meanwhile, Goku regroups with the Galactic Patrol, and, after a short sparring match, asks Merus to train him so that he might again achieve Ultra Instinct.
First introduced in Dragon Ball Z: Resurrection 'F' Chapter 2, the powerful ability allows users to react to threats automatically. Although not flawless, the technique gave Goku a major edge in his battle with Jiren during the Tournament of Power. So far, the other main players to use it have been Whis and Beerus, as Ultra Instinct is typically reserved for only the most elite fighters in the universe. Master Roshi showed something like Ultra Instinct while fighting Jiren, though he didn't quite achieve it.
So far, Goku is the only known mortal to actually use Ultra Instinct. However, he's had a lot of trouble actually tapping into the power and maintaining it. In Chapter 42, Goku even confessed to Vegeta that he hadn't been able to tap into the form since the tournament.
There have been a lot of hints that Merus, who is one of the Galactic Patrol's elite members, is more powerful than he's let on, having been capable of going toe-to-toe with Moro and a bunch of other deadly villains. Goku decides to finally test Merus' abilities in Chapter 51 by throwing an unexpected punch at him. Merus dodges and the two decide to spar.
Although he doesn't take the offensive, Merus easily dodges Goku's blows all the way through his Super Saiyan 3 form. However, he doesn't get the chance to test Super Saiyan God, as the arena starts to crumble around them. The test is enough for Goku, though. The Saiyan asks Merus to train him, much to the Galactic Patrolman's shock.
Goku explains he's been attempting to learn Ultra Instinct and that training with Merus could help him master the technique. Merus agrees, and the two make plans to train together. There's no indication Merus can actually use Ultra Instinct. Instead, it's more likely Goku is interested in Merus because of his uncanny ability to dodge and react, much like Master Roshi.
The issue concludes with Moro's forces targeting Earth and preparing to lay waste to the planet. The Z-Fighters on Earth are likely not expecting Moro's ability to absorb energy, which could have deadly consequences in a future installment.
Although Goku should be able to teleport back using Instant Transmission, Vegeta will likely have to learn an ability or something similar in order to get back to Earth in time to protect his friends and family. Still, a Goku empowered by Ultra Instinct might stand a better chance against Moro, as the transformation may not utilize ki in the same way as Super Saiyan, effectively countering the villain's ability to absorb energy. The question now is just how quickly and well he'll be able to learn Ultra Instinct, and if it will be enough.
Dragon Ball Super Chapter 52 will be available in English on September 20 from Viz Media.