Bellossom is an unfortunate story. Its inception was in the same generation as the introduction of steel types, which still handle it just fine. Its stats were not that far removed from Vileplume's, but it lacked its alternate evolution's better typing. With each generation, Bellossom suffered more and more blows. In Gen 3, it got an ability, Chlorophyll...which paired terribly with its stats. Gen 4 introduced new threats and moves, such as the improvement of flying types thanks to Brave Bird. Gen V gave it a Hidden Ability...which was worse than Chlorophyll. And finally, Gen 6 axed permanent weather. I'm not even sure a Mega Evolution could save it by now.
On a somewhat positive note, Bellossom does get Moonblast, which you can pair with HP Ground for great (but low-powered) coverage. I'd say to go with HP Fire every time, but that's better for higher tiers, and barring the absence of sleep clause, you should never bring Bellossom into higher tiers.
The risk I took was calculated, but man, am I bad at math.