If he's rolling away, Thunder jolt then chase it. If you think he'll roll back again, Side-B chase it or QuAC to hit. If he shields, grab him. If he spot dodges, fox trot forward then D-smash on his character while he's dodging. If he jumps you can QuAC then U-air or F-air into him. If he Forward-Bs, QuAC above and behind him then D-smash or F-smash him depending on where you land. If he Down-Bs run up and jump over and D-air him. Take care to avoid your Thunderjolt for either.
Chasing Thunderjolts is by far Pikachu's best use of Thunderjolt and his best approach. Oh, and to better chase it jump with forward momentum before throwing a Thunderjolt at the top of his jump, then FF to the ground and chase it.
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http://community.modnation.com/en-us/players/IvoYaridovich/creations
