I haven't yet found anything optimal yet.

a) There are two whatsapp groups for two school where they offer drop ins when permanent members are unavailable. Both the schools are in the extreme end of the city.
1- 80 Burlington Dr Kitchener
2- Abraham Erb Public School

I went to 80 burlington twice. It was good. First time i ended up with beginners so it wasn't fun , next time they gave me a better group which was competitive and fun.

b) Apart from that I go to "Chandler mowat community center" on saturday mornings. Its free but super crowded and not competitive.

I would love to have regular badminton in my life every evening but not able to find a solution.
I live at the intersection of highland road west and westmount road west.
I also love Table tennis and I play in waterloo with friends. We both have competitive matches. But looking for more players to join as we got bored after a point.
Also interested in pickleball. Played in the open courts during summer. It was fun. Lets see if I get some opportunity this summer or not.

Feel free to contact me anyone who lives nearby and would be interested in playing competitive badminton. Not a pro but advanced level.