No one is going to play with you if you have like 3 characters installed, I recommend you at least download like a "Competitive Roster", It will help you get more people to play with you in casual

Here is some character collections I recommend:

In alphabetical order:

Colosseum of Fools: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2965494064
Fungal Wastes: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2855086804
Restless Rumble: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2939620410
Second Buzz: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2870723106
Spamton's Thursday Thweepstake: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3002565006
Valiant Versus: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3309095726
Wars: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3062183010
Weeklies: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2849470264
Wild West: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2930398918

This is also important to mention, if you have a character like Ronald McDonald, 100% characters, or a characters that is really op installed there is a chance that someone will play them on you, I recommend uninstalling those characters before queuing

You have around a minute and 30 seconds to select a characters, always have a second pick as there is a chance someone doesn't have your characters. I recommend do a bit of playtesting in training mode before jumping to online to see what a character can do, you can also read the description on the character (if they have anything)