A common mistake that players can make in transitioning between VGC and Doubles OU is to copy and paste a Pokemon from one format to another, without checking that the level is adjusted appropriately. While these Pokemon will scale just fine in VGC, in Doubles OU, this can lead to a game or two where you have a severely underleveled Pokemon that may not be noticeable straightaway. It would be nice if there were a warning before starting a game in non-cartridge formats if level 50 Pokemon are being used, in a similar way to the "you have 0 EVs on this Pokemon" warning message. If implemented, I wouldn't want this warning on custom battles.
Alternatively, there could be a check added that level 50 Pokemon are autoleveled to level 100 Pokemon. Technically, this would prevent players from legitimately using a level 50 Pokemon if they actually wanted to use it, but I think that would be much more uncommon than this more common mistake of copy -> pasting sets from different formats.
Alternatively, there could be a check added that level 50 Pokemon are autoleveled to level 100 Pokemon. Technically, this would prevent players from legitimately using a level 50 Pokemon if they actually wanted to use it, but I think that would be much more uncommon than this more common mistake of copy -> pasting sets from different formats.