Well in this game i would recommend Ex-S Gundam and F91 since this mobile suits are best even with oldtypes (non-newtypes) and to be honest i always use johnny in the F91 and Shin Matsunaga In Ex-S Gundam,i would also recommend Re-GZ(BWS) cause it has a weapon that hits all units in a squad,also the GP03 Dendrobium cause it has this beam cannon atack that hits all units in a squad,more than that its totally defensive as its armor has beam negation and large beam attacks are weakened in an extent and when the Dendronium gives up you still have a chance for it will still become stamem still with weapons of a same old multi purpose gundam

The S gundam and Ex-S Gundams are particularly great Old type suits, more so for the weaker pilots due to how the ALICE system works in this game: Once the mech hits 70% hp or less the pilots stats are boosted to a certain number (75, might be different at lower levels). While this wouldn't mean much of a boost for Ace pilots, for the 2nd string sort of pilots, it's a major boost, enabling accessory characters (characters you have in a team to give boosts to a better one) to easily pull their own weight.