Yes, Merlin will be one of the founders of Fairy Tail but what happens next will be a secret.

You read the chapter in the wrong direction. Merlin is talking about the child's magical talent, not her power as an attack not to mention that Merlin has never seen Solomon, he didn't belong to that period and his eyes can't see the past. Also, Merlin never said anything about his talent compared to Mavis.

If I can consider Merlin's strength, I would say that he is undoubtedly among the best servants there are for now. His strength in the world of Fairy Tail is at the same level as Acnologia and Zeref, or between Island level and Intercontinental Level. If he is committed, he is much more, but his character is such that he will never try his best and so that his fighting level remains in this range of action. The most 'particular' things about this sorcerer are many, but the most 'interesting' things in my opinion that can represent his strength are: He can travel in time. He managed to send Bedivere through time. Creation Illusion can create such real illusions that you can't distinguish at all, no matter how much you try and what ability you use. When combined with its incubus nature, it even manages to confuse reality itself, making this ability akin to "Reality Warping." Shapeshifting, he can manipulate his real appearance as he pleases. He can be an older man, but at the same time, a child. For this reason, his true form is unknown. Clairvoyance, Merlin's clairvoyance, allows him to see through the world, allowing him to see everything in the present era down to the smallest detail, which, combined with his intelligence, allows him also to predict future events. Not to mention Merlin skill with the sword. Merlin's sword skill is said to be strong so that you can realize his versatility too. Merlin himself claims that he is 'better' with the sword and prefers to use it, but the real reason he prefers to use it is that he 'stumbles' during the spell by biting his tongue for example. Creation, he can create any object he wants and make it a physical and real object, not like Projection, in fact, he created Caliburn. Life Manipulation and Transmutation, these two abilities combined have managed to make Tiamat's 'sea' a flowery field, the same Tiamat, who is considered an entity on a multiverse level. However, these are the most noteworthy ones, in my opinion, but there are so many, too many to list of Merlin's abilities.

My mistake at that point, as soon as you told me I immediately corrected the chapter by also fixing some grammatical errors or errors of fluidity of the story. Thanks for the warning.

You will see it in the next chapters, after all the turning point is about to arrive. Not to mention the fact that Merlin is in no hurry to learn new magic, he has all the time available on his side, for the moment he wants to enjoy these moments with the little Mavis a little more.

Merlin's character is sad to be seen that way, even though I know he's canon by TYPE-MOON, it's sad nonetheless. To answer your question instead, the character who will be with Merlin has blond hair, short stature, and great magical powers. Apart from Makarov who could it be ... (❁´◡`❁) (Joking, it's Mavis)

As Reality said, the year is currently not the one in which Mavis meets Zeref. The story currently will be that of Fairy Tail ZERO. The story of the founding of Fairy Tail. What will happen this year will simply be an attack on the guild to which Mavis belongs by another. The meeting between Zeref and Mavis in the original only takes place in the year X686 when Mavis leaves Tenrou Island in search of the stolen object seven years earlier, during the same attack that destroyed Mavis's guild.