Pokémon Without changing his moveset, you have to make Magikarp the most OP Pokemon ever.

[PaperLuigi3]

How do you do it?

 

[Lancelot]

By changing his/her/it's stats.

 

[shayminskyforme88]

Baton pass attack boosts to it then let it hold a focus sash leaving 1 HP and Flail all the way.

 

[buzzing]

1.
> start with sword dance/tank/baton pass leafeon
> spam swords dance for as long as you can before baton passing
> baton pass to magikarp with focus sash and flail away

2.
> start with Salac Berry Smeargle
> spore
> belly drum
> baton pass to magikarp w focus sash
> flail flail flail