Keep a few Timer Balls ready to rely on after failing with the Ultra Balls.

I had 1 Timer Ball, and those things only become really good after 30 turns.

Get 30 Ultra Balls then, haha.

Also consider getting a Pokemon with False Swipe. Aegislash, for example.

Don't forget someone that has a Sleep move.

Venasaur and sleep powder made catching pokemon this play through sooooooooooo much easier, though I find that now all I need is a Quick Ball and bit of luck.

I'm trying to come up with a Pokerap for Kalos that includes megas.

That sounds awesome. Good luck with it.

Actually, there's a formula for Timer Balls.
1× + 1229 ÷ 4096× (0.3×) per turn passed in the battle, maximum 4×
The maximum being a 4x modifier kind of makes is useless compared to Dusk Balls (3.5x at night/in caves), though.

Unless you've got a really powerful legendary not found in a dark place.

Which means unless it's Rayquaza, I'm pretty sure you're fine :p

You stole my joke. :lol

(and only in R/S/E, since in HG/SS he was in a cave.)