If you dodge the game. the game never happened and therefore any trolling that you want to report the person for could have not of happened. The intent to Troll/INT can not be proven until the player actually doses it in game. or admits to doing so in chat.
Banning team mates picks is NOT proof of trolling. there are valid reasons one one might do so, and the system was designed to allow it because there are valid reasons one might do so.
Being upset because they were auto-filled is NOT proof of trolling, now depending on what they are saying they may be being toxic but being toxic is not proof of trolling.. Also on that note an auto filled support picking a non-support champ is also NOT proof of trolling, they were auto filled. It is quite likely their best chances of doing OK will involve them playing champs they know how to play, not champs you want them to play.
If someone is saying toxic things in pre-game chat then that gives you the forewarning to mute them at the start of the game if you don't want to listen to what they have to say.
In short. Riot can not and will not punish someone for trolling based off of champ select alone, Toxic behavior yes. Trolling no. As the hard proof of trolling doses not happen until they do it in game.