Can you check my Gyarados

Do not power up Gyarados with B/T.

Sorry, but I prefer the dragon pulse one. It is good on attacking in my opinion, it may beat a level 21 Dragonite if you power up it to more than CP 2000, as it is good in IV.

its a shame bc its iv is so great but twister is absolutely terrible. not worth a powerup at all. time to get started on your next gyarados grind- goodluck (two of mine have twister i feel your pain)

Their's tools here that u can use to do it yourself but because it has twister, its already bad,

Twister isn't awful as a defensive move, but you've still got the problem that electrics will tear through him. If (and they're far from common now) you've got local gyms of lvl8 or above you could power him up and use his massive cp to sit at the top, relying on the lower levels to offer you protection.

As an attacker you could just rely on bite but he's not ideal.

You got screwed on move set. Twister blows no pun intended.

Im powering a similar one to level 30. Though the starting cp was about 2100. Using about 1/4 of the magicarp candies I get, saving the rest for a better one. I'm at 2650 for cp it performs pretty well using bite alone attacking because of the high cp. I'm sure one with better move sets would be even better but I don't have many 2500+cp mons that aren't vaporeons

If you want a high CP defender, go for it. At level 30 your Gyarados can reach ~3000CP. But if you prefer attacking moveset then leave it in your pokemon box and power up it when you have nothing more to power up :D