They can participate, but the probability for them to win is very low because with Roobet art contest, there's a lot of good participants and most of them are digitally hand drawn and carving something into the best art. The team of Roobet knows this for sure, so we don't have to worry about that software or if they won using other's picture or art, then we can raise that concern into the right thread. Few days left before the end of the new contest, better to focus on that.
Can't say with guarantee that team finds which type of art more creative and interesting as there is no limits for being creative mind and you could make simple art or say if AI is allowed then you can be extra imaginative in it to show your talent.All the participation are well talented and all entries are good but last result depends on team hands.