To whit, I've traditionally tried to build monster/creature/predator stat blocks to model the PC ones - so far, so good. However, I've traditionally tried to build creatures using the same structures and restrictions as the PCs - so, if a level 4 PC has 7 ranks in dice and 15 ranks in traits, then a level 4 creature should have 7 ranks in dice and 15 ranks in traits. I've learned over the last while that just by reversing this thinking - 22 ranks in dice and/or traits = level 4 - you can build custom creatures more easily, and you can remove artificial barriers that force you to create balanced but sometimes counter-intuitive builds. I've found it is very easy to build predator stat blocks, and to still have variety among a range of creatures of comparable levels. Here are stat blocks for small tree frogs and small chameleons, to give you an idea of how these come together:
Chameleon, Small (30 QPs; Level 6; 6D10 Hits; Save +3)
Body D10; Prowess D12; Spirit D10; Strike D10
Attack +3; Bite +4; Invulnerability +1; Regeneration +2; Speed +2; Stealth +5
Bite (att D12+3/dmg D10+4)
The chameleon attempts to close in on its prey, using stealth (blending into its environment) to get a surprise attack.
Tree Frog, Small (26 QPs; Level 5; 5D12 Hits; Save +3)
Body D12; Prowess D10; Spirit D8; Strike D10
Attack +3; Constriction +4 (Tongue); Leap +4; Tongue Attack +3
Tongue (att D10+3/ dmg D10+3)
The tongue attack can strike a target up to 3 units away. A target struck by the tongue is pulled into the mouth of the frog, suffering D12+4 hits (no soak allowed) on each turn the frog takes. Once the target has been killed, the frog swallows it. A creature attempting to break free of the frog’s tongue must use 1 turn to attempt this, rolling Body + Might vs. the frog’s Body + Constriction resist.