if you train it well than it will be good.
OK ampharos is a good Pokemon it looks weak but it is strong. Now you're probably wondering what moves he/she should learn well to have a nicely balanced ampharos it should know:
Charge beam/zap cannon
Thunder punch
power gem
signal beam
Oh you might want to give it a zap plate to boost your charge beam a little bit
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The only way you can get an ampharos is to catch a mareep then level it up to level 30. You can catch a mareep on Route 32, 42 or 43. Good luck ^^
You can get Ampharos by evolving Flappy which you can get at route 222 (with Pokeradar) but it's uncommon.
I believe Ampharos is somewhat based off a Kangaroo shape figure.
Really good ones
Flaaffy evolves into Ampharos at level 30