Musclekarp appears to be an angry Magikarp on top of a pink, muscular body it appears to have the Superhero Package from the ROBLOX catalog. The body has another Magikarp tail on its back.
Earned by redeeming a code on one of Uglypoe's Twitch streams. The new code, FishyFishy redeem it while the code is still around. The code ThirteenMillion is Expired though, so uh..yeah.
At LVL 100 Musclekarp's stats
208 SP. ATK
208 SP. DEF
Splash - Level 1
Double Hit - Level 15
Close Combat - Level 30 (Not available)
Bubble Beam - Level 36
Brick Break - Level 45 (Not available)
Water Pulse - Level 54 (Not available)