For a chiyo lineup, there are quite a few major flaws that comes to mind:

1) You have to build a team that centers around her. Earth main comes to mind first, since has Repulse->Knockdown chase. You also need Gamaken to increase no of chase. If opponent have control type team or nuke team, can seal/kill your chiyo quickly and you'll be in trouble.

2) You might have noticed already, but any character that have chase that triggers more than once, the dmg is kept lower to balance things out. This is even more true for chiyo and her chase does low dmg/chase. What makes it even worse that chase is nin type and her ninjutsu growth is very bad. So to make her effective, you have to give give nin boost in the form of gear, tools, megatama battle armor etc.
3) We recently had sailor sakura. Try using chiyo on her and she will just heal those low dmg inflicted. ;P

However, if you can make it work, all this chase can do some considerable dmg overall.