It should come as no surprise to anyone that has played Competitive lately that the state of the game has deteriorated immensely, and in particular, the frequency of meta-friendships has increased greatly, mainly due to the smaller player-base. Meta-friendships have always been around, but only now has it gotten so out of hand that it's hard to find a single round in which it hasn't occurred. Personally, I blame pranay for stirring the pot and basically encouraging this sort of mentality as the 'optimal' way to win a trophy.
In order to resuscitate EM's competition and restore a sense of legitimacy to the game, we need to take a three-pronged approach to rectify the underlying issue.
Redefine Cheating - First, we need to segment the current definition of cheating. A general cheating definition is fine, as it covers the specific instances of outright cheating. However, we need a separate violation for Multi-accounting (in the same game), which should, in my opinion, be an instant ban. More importantly, however, we need to endorse meta-friendships. They are unpreventable and need to be outlined as an acceptable strategy.
What is a meta-friendship? A player joins with another player with the intent to help that other player win, so long as they still abide by their win condition (might want to rephrase this so it makes more sense in contrast to Gamethrowing). Yes, you heard me right, and you'll understand why shortly.
Limit Players to 10 Comp Games with Any Other Player in a Given Round - We need to somehow make this a rule. Ideally, lucid could code us something that bars entry into a competitive game that has a player the runner has already played 10 games with. Ideally, this would be account-wide, barring alts from swapping in. I think 10 is a very generous amount, but the point is still there: we can't stop meta-friendships, but we can limit how often you do it and with whom. We may not be able to stop Ruse, for example, from joining each other's games, but I think after 10 with the same person, it's reasonable to say their run has been, at the very least, boosted by that other player's presence. Anon games won't work to prevent meta-friendships, but this will.
More than likely, lucid will not be willing or won't be around to code this. So I suggest this be made an announced rule and mods simply warn players that pass 10 games and then suspend if they do it. Believe it or not, in any given round, it is actually hard to play more than 10 games with 1 player, if you are joining games randomly. We need this randomization to deter extensive meta abuse.
Remove/Limit GY Vision in Comp - This is the major one. This is the one method we have of curtailing serious cheating in EM competitions. Ideally, we have lucid code it so that GY vision in comp games is equivalent to a blue that is still alive (i.e. see nothing do nothing in night sequences). However, simply removing GY vision, at the cost of spectating, is still an effective solution. If you care about legitimate games, you should want this and suffer to review the game if you really want to spectate. Still, the ideal solution is a great one and allows for non-intrusive spectating.
TL;DR The only way to counteract excessive meta abuse by friends is to 1) redefine cheating by endorsing meta-friendships (and defining them), 2) limit the amount of meta-friendship directly by player-to-player, 3) remove GY vision as a viable tactic for undetectable, serious cheating.