How to balance these random champion gamemodes

I've played a lot of aram in my day, and gamemode with champion selection being randomized. This had become more and more noticeable for me with ARURF but there should be a system for balancing teams. Having a random champion is fun and is one of the more enjoyable parts of aram to me, but the fact that we can have champions that all suck completely, and the enemy team having 5 champions that are really good, ends in games that are one sided even if the players skills are around even and makes the game not fun.

One of the thoughts that I'd had over time is to implement a pseudo-tier list of sorts to balance these random teams. What this means is either giving a champion a score (from 1 to X where X is the best and 1 is the worst) or a simple tier chart (S, A, B, C, etc...) so even if everyone is getting a random champion, both teams will have an equal amount of good/bad champions, and in a scenario where both teams have equally skilled players, a player who has greater knowledge on the champion they randomly got would increase their teams chance of winning, and increasing the equality of the game between both teams, making it close and enjoyable.

Completely random is hard to do, and in a competitive game, it's never really a good thing,

Cheers [slayer-jinx-catface]