Assuming you fail phase 1 this is a guide to give you some insight with the many matches I've won as the separatists.

1: AAT. The AAT is essential and should always be chosen when possible as they provide a significant amount of firepower that brings down the walkers in <30 seconds. Use linked fire and get the star card for increasing the time as linked fire does more damage in less time than the siege cannon.

2: Using the droideka to roll below the walker and start firing on it is a good way to deal damage however it doesn't do a lot of damage and can take a long time to kill the walker not to mention that you will probably be killed by a sniper in less than 10 seconds after deploying. Personally I see this as a good option if there are no AAT's available and this can also help your squad spawn on you with heavy's.

3: supercharged sentry. The supercharged sentry is the best thing you can use against the walkers as a trooper as they can deal ~200 damage in during their runtime which is very high for the timeframe.

4: iden pulse cannon. Idens pulse cannon is a very effective weapon and easily will determine the difference between victory and defeat as it can eliminate a walker in less than ~30 seconds and is good for shooting anyone that tries to get in the walker. It does about 40 damage per shot I believe based on testing.

5: NT-242 disrupter shot. The disrupter shot from the NT-242 does about 24 damage per shot and will do a significant amount of damage over time making it a great weapon against the walkers.

6: T-21 burst fire. The Burst fire of the T-21 does a significant amount of damage to the walker in a small amount of time and should be used in between supercharged sentry ability recharges.

7: stap speeders. You can use the stap speeders to quickly get across the map with the aim of flying behind the walker then jumping off and using supercharged sentry to Open up on the walker while also allowing your squad to spawn on you so they can do the same.

This is what I have tested and found works well against the AT-TE walkers on geonosis and most of this also applies to the walker on felucia too.

Thank you for reading and I hope this helps anyone looking for any tricks for b Taking down these big beasts on the battlefront.