I have been farming for stickers on Brawl the past two days. Last Monday during our weekly get-together, we played Brawl for the first time in months. I remembered the only challenges I had yet to unlock: collect 500 trophies, collect all (700) stickers, beat boss battles on very hard, beat boss battles on intense. The last time i finished a challenge, I was still in college.
Then, yesterday, I had a breakthrough. After some SSE and coin launcher, I collected 500 trophies.
I have moved on to sticker farming. I use a sticker factory custom stage. I use Bowser on Special Brawl, with Mega and Fast enabled. Now I only have 21 stickers left.
Maybe I will finish it this time.