How to overcome such a strong trainer in game

Hi guys, I am playing Pokemon Star Sapphire and being stuck at route 112 because I have no chance to defeat Ace Trainer Wilton. He has 6 pokemon, they all have higher level than my pokemon (40+). The questions are:

  1. How can I defeat him.
  2. Why is level in this game higher than the same game I watch on youtube? Something wrong? I have not got the third badge (Fire-type) because I can not overcome route 112 and soon, I think I can not control my pokemon because they all level up to 40+ while I am having 2 badges.
    Help me, please. Thank you a lot.

Can’t help you in this situation but the 3rd gym is electric in mauville city

You’re not supposed to. Route 112 was designed to be tackled after defeating Wattson, the third Gym Leader in Mauville (which is around level 35 or so). Route 112’s recommended level is 42.

If you Google around, you should come across Dio Vento’s Wordpress (the person who made the hack). They put together a Strategy Guide which is linked in their Rutile Ruby/Star Sapphire post which, while incomplete, gives you an idea of the order you have to go in and the average level you should be when you enter that region.