Jigglypuff has 50, Mankey has 40. This is very important, as against a Slowking, if you Taunt/Tempt out a Slowking and they Switch/Balloon Berry out of trouble, Umbreon just needs one Darkness to KO the monkey (likely to happen) while it needs to have 2 DK energies (and therefore no Rainbow) to make Jigglypuff go down for the count. Also, Mankey on the bench gets taken out by 2 of Murkrow's Feint attacks, while Jigglypuff can survive.

Both attacks mightily bite, so no points go out. You'd almost never use those attacks, as Brock's Mankey isn't for Fighting decks or Brock's Primape (if you think so, that's like thinking Jungle Scyther is for Grass decks just because it has a Grass attack, and is meant to evolve into Scizor just because it can). Sing is a bit better, but it's inconclusive, since if you DO just happen to play Fighting, this little monkey can KO a Pokémon a Focus Band has kept in play (just like playing Scyther with grass gives you a small additional bonus!)!

Mankey falls to Psychic threats, Jigglypuff to Fighting. Let me put it this way. What should you worry more about your opponent using: a Sabrina's Abra or a Gligar? However, Jigglypuff's HP, again, forces your opponent to use a Pluspower to KO the puffball.

Other things means Brock advantages. In a Brock's Sandslash deck, I think Mankey would do best, as if you needed it you could Training Method for it (although that would be hard if they used Slowking...). In a Fighting non-Brock deck, it depends on which fighting. If it's Psychic-weak then use Jigglypuff, if Grass-weak use Mankey. Any other deck should use... whatever you feel like. Seriously, whatever you want. I've laid out the pros and cons, but... the only other thing besides my closing point is that if a deck is Psychic-weak, use Joggly (duh!). Also, I put my point down here so that if you're just skimming you won't be able to find the point, and you'll have to read the entire article to find it! Anyway, a great point about Monsieur Puffball is that it can turn into Wigglytuff, because Wigglytuff can hurt BAD against Slowking, Jiggly can nail it, and can Brock's Mankey evolve into anything good (Okay, Brock's Primeape bites times a trillion)? Also, if Iggly is Mean Looked, that can hurt... until you evolve it into Jigglypuff! Note that most non-damaging Pokémon are very vulnerable to Murkrow (in fact, when I first saw Jigglypuff, the first thought that crossed my mind was "Murkrow bait"), but these guys can gust out the Crow, ending the "look".