Currently dig/fly are banned from Gen 1 OU. This is because if a pokemon is paralysed on it's first turn it is invulnerable until it switches out or completes the second turn of dig/fly.
Firstly, there is a simple solution to the problem of pokemon becoming invulnerable when paralysed on their first turn - prevent the player from selecting any move other than dig/fly until the move completes it's second turn. This would be enforceable on the cartridge games, it doesn't change the mechanics like Counter (to remove the desync) and Wrap (you can see if the other moves are greyed out or not).
Secondly, I think allowing dig/fly in OU/UU will make more UU pokemon viable and provide a way to avoid explosion/self destruct. These moves are no more 'unfair' or 'broken' than wrap, or the 10% freeze rate of ice beam.
Firstly, there is a simple solution to the problem of pokemon becoming invulnerable when paralysed on their first turn - prevent the player from selecting any move other than dig/fly until the move completes it's second turn. This would be enforceable on the cartridge games, it doesn't change the mechanics like Counter (to remove the desync) and Wrap (you can see if the other moves are greyed out or not).
Secondly, I think allowing dig/fly in OU/UU will make more UU pokemon viable and provide a way to avoid explosion/self destruct. These moves are no more 'unfair' or 'broken' than wrap, or the 10% freeze rate of ice beam.