Ho-Oh and Reshriam Ex

So I am recently new to how the trading card game works and I'm not sure if this is the right forum but I was wondering if It would be possible to make a Ho-Oh-EX and Reshiram-EX based deck or would it too inconsistent but if possible what would i need to counter sigilyph so i could damage it? Also another quick question about the game in order to compete at a regional competition would i need to qualify or is it open?

I'd think a deck using the two would be too inconsistent, personally. Reshiram and Ho-oh are both pretty slow compared to other EXs, unless you gear a deck toward bringing Ho-oh out of the discard pile to be ready to attack.

Also, Regionals are open to all.

Well, you could run a Ho-Oh/Tornadus deck with one or two Reshiram as a side attacker, but if you're trying to make a deck built around Ho-oh and Reshiram together, you're not heading in the right direction for a good deck for a tournament.