1 minato isnt a bug to itachi.... he can simply throw kunai around the battle ground and push him back by spammiung rasengans etc. teleporting to avoid amaterasu and tsukoyomi etc. then if itachi gets over a kunai game over , minato is even more of a tactician than shikamaru so he would beat itachi ftg or not...
2: sasukes chakra is just above average tbh... nowhere near narutos level , but its slightly higher than average ... susanoo uses a huge amount of chakra so if you play a long game vs itachi as long as your fast enough or have enough defences etc. then you would rape stomp with low difficulty ...
3:i watch anime and manga.... do you? zetsu said the sword of totsuka can only seal living BEINGS not jutsu.... yata mirror doesnt cover itachis back nor does it go under his feet or above his head.... tbb... shinra tensei... chibaku tensei,rasenshuriken,chakra arms etc. all can destroy itachis susanoo from behind and tbb can probably smash the mirror too. on top of that susanoo is only a last resort , here why; the chakra it uses is immense , it is a last line of defence when all else fails , in the same way a big finisher is used ... susanoo cant be maintained for very long if you have low chakra levels , susanoo is about as painful as spraining every muscle in your body , so you cant fight after youve used it. there , i disprove u