Okay well looking at your team, your top common weaknesses are Fighting, Fire and Ice. As Kangaskhan and Hydreigon are weak to Fighting, Doublade and Roserade and weak to Fire and Roderade and Hydreigon are weak to Ice.
Therefore to counter these threats I recommend that you use a Pokémon such as Aerodactyl. The reason I recommend Aerodactyl as your last option is because Aerodactyl is a Rock/Flying type which means it covers each of your weaknesses. As Rock covers Fire and Ice and Flying covers Fighting. It also is a good physical sweeper with 105 Attack and 130 Speed. Granted you can't give it it's Mega Stone because you already have Kangaskhan with it's Mega Stone but you can run Aerodactyl with a Choice Band making it even more powerful in attack than it's Mega Evolution. You can also run Stealth Rocks on Aerodactyl seen as though you don't have a Pokémon that can set up Stealth Rock's in your team. If you decide to give Aerodactyl Stealth Rock it may be a better option to give Aerodactyl a Life Orb instead of a Choice Band so it doesn't have to switch out after you use Stealth Rock.
Aerodactyl (M) @Choice Band/ Life Orb
Trait: Rock Head/ Pressure
Nature: Jolly (+Speed, - Special Attack)
EV's: 252 Attack, 252 Speed, 4 Def
Stone Edge (STAB + Increased Critical Hit Ratio)
Aerial Ace (STAB + Never Misses)
Earthquake (Covers Electric, Rock and Steel Weakness)
Aqua Tail (Covers Rock Weakness)/ Double Edge (120 Power and No Recoil with Rock Head)/ Roost (Heals Aerodactyl)/ Stealth Rock (Set Up Entry Hazards)