There's been lots of threads on this - read what they say about the "plate" on the shoulder.
I like 375HH myself, or maybe 458 in heavy cover. I like a 44 sidearm, but a 10mm or 41 might be reasonable.
One of my buddies downed one with a 308, and it was still trying to get up and come after him - and I shot it SIX TIMES IN THE HEAD with a 1911 at point blank range (about four feet). At the end of those six shots it was more in death throes than purposeful - but do you want to be trying to stop a charge with 45ACP?? Ha.
People will tell you about killing pigs with 22LR, and I don't disbelieve them - if you have the drop on Mr. Piggy. Also, the fraction of domestic pig to wild boar makes a big difference - in Texas lots of our wild pigs are nearly pure boar.
Javelina is not the same AT ALL - smaller, not good to eat, not so tough, and won't try so hard to kill you.