When using Palkia & Dialga LEGEND's "Time Control" attack, can you place more prizes than your opponent started the match with?
Yes, you can. The prize pile is not limited to any maximum amount.
Source: Triumphant FAQ (2010-11-04), PUI Rules Team (2010-11-04)

Relevant cards

Note: All applicable cards may not be listed below.
HGSS4_101
HGSS4_102