Hi, I've been working on the Super Singles in the Battle Tree. I can consistently get to battle 42-44, but seem to have reached a wall. The team notably lacks bulk, all three team members are offense-oriented, but their ability to get so close to victory so frequently makes me think they could win with only relatively minor adjustments. Also, as a side-question, I'll have to replace one of them for the final battle against Red, so I can get the ribbon on my Chesnaught, so any suggestions for that battle in particular would be useful.
Dragonite
Ability: Multiscale; Item: Flyinium-Z; Nature: Adamant
252 Atk, 252 Spe, 4 Sp.Def
Dragon Dance/Fly/Earthquake/Extreme Speed
The lead and a physical sweeper. Multiscale means Dragonite can pretty reliably take any one hit, letting it set up with Dragon Dance. After this, it can reliably sweep with Supersonic Skystrike, Fly and Earthquake. Mamoswine, Beartic, Avalugg and Vanniluxe appear pretty frequently, forcing me to switch. Cofagrigus and Toxapex are sometimes hard to deal with due to their bulk and Gyarados and Wishiwashi also pose a threat.
Sylveon
Ability: Pixilate; Item: Choice Specs; Nature: Mild
252 Sp.Atk, 252 Sp.Def, 4 HP
Hyper Voice/Shadow Ball/Psyshock/Round
A special sweeper. Pixilate+Choice Specs+Hyper Voice means that it only really uses one move. Useful for breaking physical walls and for extra type coverage. Sylveon is probably the least-used team mate, but invaluable in certain situations. Shadow Ball is used pretty often and Psyshock has been used once, Round is never used.
Kangaskhan
Ability: Scrappy (Parental Bond when Mega Evolved); Item: Kangaskhanite; Nature: Adamant
252 Atk, 252 Spe, 4 Def
Return, Sucker Punch, Earthquake, Power-Up Punch
Parental Bond+Power-Up Punch means that Kangaskhan's Attack is raised twice with every use. This means that it can pretty quickly snowball into a menacing opponent. Even without that, its maxed friendship means an unboosted Return can two-shot most pokemon. Deals well with Ice types that Dragonite can't handle, whereas Dragonite takes the Fighting types.
Strangely (based on the team composition) we've lost twice to Breloom. Its speed, Spore and physical prowess means it has been able to sweep us and win.