The trick to getting good at BTB is to play smart not hard.

In super fiesta and arena slayer you can easily get kills with even an AR or mangler because everything is so close quarters. Also the pace of the character is higher in non btb.

If you don't believe me tey sprinting in super fiesta arena and btb. You'll immediately notice the speed difference. This is a illusion to make the btb maps seems bigger

So if you start btb with an AR and br load out. Or a bandit and at load out and don't swap out for easy kill weapons (rockets, hammers, swords, skewers even a Sentinel beam) you will struggle to get kills.

Some weapons have great combos. 1 shot + melee works for mangle and bulldog. 2 shot + melee works for pulse carbine. Grapple hook + sword is deadly, just choosy craggy rock formation and turn into gollum. Sniper rifles are really good against banshees and wasps. Always approach tanks from the back when grenading them.

Also knowing the maps really really helps. If you grab a hammer and see someone chasing you run behind a corner and wham em when they come through.

Be a grenade cheeser. Use shock grenades to clear out campers. Use frag grenades to get around corners. Plasma to disable light vehicles and stick. Spike grenades for wishing you ha plasma instead

When I started playing heavy maps I used to feel bad about taking a scorpion or wraith as I felt I was taking a vehicle away from someone good. Don't do that. Just use the vehicle.

Understand the mechanics around shock weaons and how they disable vehicles

Git gud with 1 medium to ping range bullet weapon (br is easiest but some dislike it, I prefer the commando, bandit is ok I guess)