I'm not sure if it's a cliché or a fact that every noble or lord or promising prince or whatever they called them back then has this guide, this helper, this advisor that are way smarter then them.
Was that really the case back then? If so, how come? I mean aren't royalties supposed to be the educated ones, ones with the broader visions in any case? Smarter, better. I'm not saying they had to be the geniuses or advisors couldn't have been just simply bunch of smart people but nowadays, almost every tv show for example, has these side characters that are often ignored even though they are clearly smart.
Is it because of their upbringing, their social status? I mean are they smarter because they know about poverty, being a commoner, having limits in their lives so that it give them more perspective? Are royals' or noblemen's judgements doomed to be clouded because of who they are? Being out of touch with their folks and others? What made these advisors so wise that royalties couldn't see what they see and how come? Is it really not a brainer or something to think about?
Giving off a description of an average lordly court is an hellish endeavor, simply because these social groupings didn't maintain (or even have) a default structure to begin with, and have changed drastically over the course of a millennium of Middle Ages.
I believe that the cliché of the king being an imbecile puppet of ruthless courtiers and cutthroat advisors is something born of the post-Illuministic perception of courts during the years previous the French Revolution (what historians call "Ancien Régime" or "Ancient Regime", with kings seen as decadent, lustful and completely inept at ruling. This could have possibly been amplified by the historiographical perception of the Renaissance courts as being violent and plagued by palace intrigues, murders, conspirations and the like, all woven by traitorous courtiers and relatives which were confidants of the lord. Take for example Game of Thrones, or Medici: Masters of Florence or both the Borgias series.
What we know of medieval kings and lords' advisors tells a different story however. I will make a couple examples.
Louis IX (1214-1270), king of France and saint, is known to have employed at his court as chaplain and confessor Robert de Sorbon, the cleric who later founded the university of the same name whom, being the king a very pious man, was questioned when matters of faith or a doubt beset the ruler. In the same moment, Jean de Joinville (1224 ca.- 1317), knight at the service of said king, wrote a chronicle of his life and in it and in some other accounts, he recounts being a very close friend of Louis IX, often discussing and advising the king, even when being scolded for answering in a manner which angered the sovereign.
In general, advisors of a ruler were those people who lived in his court or holdings and that he himself questioned when in doubt over something, like making alliances or war, or what side to choose in moments of great turmoil and possible civil war. I would say that most times, at least one cleric was present, virtually in all cases as chaplain and confessor, or as representative of a nearby ecclesiastical power (i. e. a monastery). Perhaps a close friend, a relative, or a specialist could be kept at reach in order to quell a problem the ruler faced. Most of times other nobles upheld these functions, even if I am not sure they were formal in nature but rather practical, like simply being on your lords' good side and being invited over for dinner and discussing with whom he should marry his daughter. However, it wasn't uncommon for close nobles to have positions withing the king's administration (for example, as judicial officers or chancellors like in the court of Charles I of Anjou in Naples) and being advisors and confidants of the king.
I do not believe that rulers needed advisors because they were inherently dumber than the others to rule. Neither I think that advisors were universally better than their liege and took advantage of this. Such instances might have happened indeed, but more in general I believe that lords and kings sought the counsel of other people for the same reason all people seek help for, especially with scholarly and religious matters as landed nobility, which was mostly a warrior aristocracy, was not well-read in either scriptures or academic matters in the vast majority of cases, and thus sought the advice of those who knew more.