The Intermission's Shop option will have a list of expensive Enhance Parts and Units from the FMP and SEED series for sale. Press X for units and Y for Items.
To unlock this feature beat the game once.
Begin a mission, any mission. When your motherships appear, and you go to the select mecha screen, press X. Unequip all parts from mecha, and sell them. Then, begin the mission, and fail. You will be taken to the pre-mission screen, with all the money from selling the parts, and the parts you sold. Repeat as desired for infinite money. It's possible upgrade every unit to the max this way as soon as you obtain them.
To unlock the following bonuses, insert one of the following Super Robot Taisen cartridges into the GBA slot and Super Robot Taisen W into the DS slot, then load an Intermission file in SRWW. A message will indicate that you have received the corresponding bonus Part and Gold.
Soul of Dai-2-Ji SRW - Insert Dai-2-Ji Super Robot Taisen
Soul of SRWA and 30000 Funds - Insert Super Robot Taisen A
Soul of SRWD and 50000 Funds - Insert Super Robot Taisen D
Soul of SRWJ and 80000 Funds - Insert Super Robot Taisen J
Soul of SRWOG and 60000 Funds - Insert Super Robot Taisen OG
Soul of SRWOG2 and 70000 Funds - Insert Super Robot Taisen OG2
Soul of SRWR and 40000 Funds - Insert Super Robot Taisen R
Duel AS - Stage 45 have 1 battle conversation with Dearka then convince Yzak with Dearka Stage 51 let Yzak retreat after defeating Regenerate obtained at 52
Hyperion - At Stage 50 Plants Route, bring Hyperion (Canard)'s HP below 50%, have 1 battle conversation with Kira, defeat Hyperion with Prayer(X Astray)