For XY formats; Yanmega can trade well with many EX mons with a t1 120 attack thanks to forest and it's ability. Octillery helps with drawing close to 4 cards. Loses to night march if you don't find muscle band to ohko pumpkaboo, as well as ability locks. If goodra is played, use yanmega break to get in 100 dmg unaffected by stuff like Giratina tech.