Link is not OP, you just do not know what to do against one, something that if OP was Bowser in 0.9.0
Variant Items is the variant that is fair, that of the hidden abilities if it is OP, just do UP + B and believe me, that you will always win,
It's different that you do not move so much and do not react much, I'll show you a video of mine doing combos (https://www.youtube.com/watch?v=PfrDcLPgGNk) use everything you have
no character is stronger than another, each one has an advantage that another does not have,
example:
Sonic has a high speed and his attack B (homming attack) can be stopped with a Smash UP (Up + A) and you can easily defeat him
In short, you must be faster with the characters if you want to beat your brother, I have a friend who does a lot of UP + B spam with Link Hidden Skills, and believe me it is annoying, but even so it can be won, simply Link has a too long range and an absurdly large force