Without much rambling I present you my favourite and least favourite grass type Pokémon.
Picking my favourite grass type was something I underrestemated. There are so many creative, cool and excotiv grass Pokémon and I feel bad for only naming one, so I'll name a few who almost came out on top such as Breloom, Victreebel, Ludicolo or Roserade.
Tropius still is something special to me ever since I used one as my main flying Pokémon back in my Sapphire days.
A huge, bulky dragon-like grass Pokémon isn't new as seen a generation earlies with the Chicorita-line,but I found Tropius not only more useful ingame ( one of the best HM-slaves ever) I prefer its design greatly. The whole banana-gimmick may seem a little stupid but it is adorable in my eyes. It's good for 'roleplaying' too because it is fun to imagine the trainer eating regularly from Tropius' fruity snacks in order to survive on his/her harsh adventure.
I like many grass Pokémon but I have to say that a lot early-stage grass type are rather uninteresting. I had to decide between Cottonee, Petilil, Budew, Exeggcute and Oddish but in the end I had to choose Petilil. It just isn't interesting to me at all nor does it have much personality or a cool or even funny gimmick. I like its evo, but someone had to be the least favourite.