Direct Quote from Petopia:
"Charge 4: Pet Level 36 (17 TP). Charges an enemy, immobilizes it for 1 sec, and adds 250 melee attack power to the boar's next attack.
No known creatures have this skill when tamed"
Unfortunately no one has found a Rank 4 Charge on any Boar. This is due to the fact there are no 30-40 level boars. The highest level boar you can get is 26, then it starts over again at level 48. In between 27 and 47 there are no boars at all in the game. This is where Rank 4 Charge would of come into play. Pet level 36 is where you would have learned it, but seeing as there are no level 36 Boars you cannot learn Rank 4, you must wait until lvl 48 to learn Rank 5 unfortunately.
You may also notice that Boars get the ability called "Gore". Ranks 5 and 6 you are unable to learn because you would need to find a boar that is level 32 for Rank 5, and a boar that is level 40 for Rank 6.
Quote:
Also, Wolfs are more fun then Boars ^^b
You can always use a Wolf as your pet. People just suggest boars because of their stats and versatility.