Every team has weakness, if Bayern Munich face Manchester City in the Champions like league I don't think they will win Manchester City that easily. When you said we can find a weakness I Bayern Munich team I just laugh. I like the champions league because big teams will eventually meet each other and I know Bayern Munich will want to avoid Manchester City till they meet in the finals.
Indeed, no team is perfect. Each team must have their weaknesses, but some teams may have a better way to deal with their weakness. It is the role of the coach to know how to deal with the weaknesses, that's why it is very important to have a smart and experienced coach. To win the UCL title, it is a must to have a coach who has a good record. It proves that the coach understands how to deal with their weaknesses and brings out the team's best strength.
Sure, it won't be an easy match if Bayern Munich will play against Man City. Moreover, if Man City can play with their full teams, Man City even may have a better chance to win the match. Guardiola has a lot experience in UCL matches both as a player and a coach. So, no doubt if Bayern Munich will be difficult to beat them. Yes, Bayern Munich must always expect to meet Man City in the final round only.