What does buddhism say about bodybuilding (and weights training)? Bodybuilding and powerlifting are making us stronger and more manliness, body can produce more testosterone and we're generally healthier. Yes, there are some bad things about this like anabolics or synthol, but in general - can someone who trains with weights become buddhist? Are they too agressive in eyes of buddhists?
These practices are seeing just like any other sport that does not involve morally problematic activities like killing or hurting other beings: it's just a sport. I don't think power lifters et al. are seen as aggressive -- not like, say, bullfighting or any other blood sport. 

But things might be different for a buddhist body builder or power lifter. In the buddhist training, there is a spectrum from lay to monastic, and in that spectrum, the inclination to engage in certain activities change.

For example, a lay buddhist might take to heart five buddhist precepts:


I undertake the training rule to abstain from killing.
I undertake the training rule to abstain from taking what is not given.   
I undertake the training rule to avoid sensual misconduct.
I undertake the training rule to abstain from false speech.   
I undertake the training rule to abstain from fermented drink that causes heedlessness.


These are among the most basic buddhist training rules that enables one to practice buddhism and none has anything to say about body building  -- or sports for that matter (but drugs that cause heedlessness are breaking the fifth, which may obstruct the person's practice). So, lay buddhists can normally practice sports like body building etc. One of the main points of evaluation is ethical conduct and many sports do not present an ethical problem.

Now, a more committed lay buddhist might take some extra precepts, like:

I undertake to abstain from singing, dancing, playing music, attending entertainment performances, wearing perfume, and using cosmetics and garlands (decorative accessories).

Taking that vow likely conflicts with watching and participating on competitions. Even though, strictly speaking, it might not be a problem if one just wants to practice the sport, a person more committed to buddhist training might be less inclined to partake in activities that might hurt his or her buddhist training progress.

In the end of the spectrum there's the monk or nun. They are unlikely to devote themselves to activities that require too much (of time, energy, money, etc) and that do not benefit / or creates obstacles to their buddhist practice.