Venomoth is already being moved back to UU.
Anyway on the subject of Arcanine, if i move him to BL, this would be the same as saying "you cannot use Arcanine in UU." Just because a pokemon is UU is not saying they cannot do well against any other pokemon, it cannot be used in Standard play. Tangela is also really good in RBY. It has great defenses and can Sleep Powder and Swords Dance. It can definitely do well in standard play, but it just isn't good enough to be what it is. (The same could be said about many pokemon) As a starter Arcanine really only scares Eggy and Jynx, and after that it is pretty useless. Zam can PAR it and Psychic it down. Starmie can do the same (except with TBolt) Gengar isn't afraid of it at all. Its 318 stabless attacks aren't exactly a huge threat to chansey. A counter chansey completely owns it. it cant really switch in against anything except exeggutor and it wont be packing a huge hit on whatever switches in to counter it. And the way you people seem to be describing Arcanine as just a kamikaze without care of what happens to it, it will most likely have some sort of status effect on it very quickly which it will not be able to recover from. a paralyzed arcanine is about as useless as a pokemon can get. while i admit i have never used arcanine, i have definitely faced many people who have used arcanine and it has never been a pokemon where ive thought, "hey that is a pretty good pokemon that could be of some use..maybe ill try it."