I wanna know how can I do that if there is a way.
There is but one way... Skill Link! This ability maximizes the amount multi-hit moves hits. Although some moves like double kick stays the same, with or without Skill Link. List of moves Skill Link affects:
Arm Thrust Barrage Bone Rush Bullet Seed Comet Punch Double Slap Fury Attack Fury Swipes Icicle Spear Pin Missile Rock Blast Spike Cannon Tail Slap Triple Kick (gen 5+) Water Shuriken
Edit: Oh yeah, there's one more way but it only applies to Mega Kangaskhan. It's ability Parental Bond, makes everything hit twice so it must make multi-hit moves hit more than normal right? Nope, I'm glad I checked Parental Bond's Bulbapedia Page before editing that. Parental Bond does make every one hit move into a multi-hit move though.
Hope I helped :)
Source: The link above