Seismic Toss and Body Slam are illegal in VGC2019, they're transfer moves from gen 3, VGC2019 only allows gen 7 origin. Although for formats that do allow it, Body Slam on the mega is amazing as it gets that double paralysis roll. What I generally see in doubles is something like this:
Kangaskhan @ Kangaskhanite
Ability: Scrappy
EVs: 4 HP, 252 Attack, 252 Speed
Jolly nature
- Fake Out
- Rock Slide
- Double-Edge / Return
- Drain Punch
Kangaskhan can run a lot of moves, but one of its primary utilities is Fake Out support which you see on virtually every Kangaskhan in doubles. With STAB and that extra hit it actually deals significant damage with Fake Out too. The normal move depends on preference, Double-Edge hits harder while Return avoids recoil. You might want to run Stomp here if Minimize Chansey really bothers you, it also gets a double flinch roll, but it's somewhat weak otherwise. Rock Slide is spread damage and can cause flinching, and has a double flinch roll if the opponent only has a single pokémon on the field, although it doesn't benefit from Parental Bond if attacking while the enemy has two pokémon on the field. Drain Punch is recovery.
For the Battle Spot doubles it can also run Power-Up Punch from the 6th generation, which acts like a Swords Dance that deals a bit of damage. It also has other moves like Sucker Punch, Low Kick, and elemental punches that it can use. As long as you run Fake Out and a normal STAB move the other two moves can be a lot of different things depending on your team and what you want to cover. It's quite a flexible pokémon in that regard.